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A173018
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Euler's triangle: triangle of Eulerian numbers T(n,k) (n>=0, 0 <= k <= n) read by rows.
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121
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1, 1, 0, 1, 1, 0, 1, 4, 1, 0, 1, 11, 11, 1, 0, 1, 26, 66, 26, 1, 0, 1, 57, 302, 302, 57, 1, 0, 1, 120, 1191, 2416, 1191, 120, 1, 0, 1, 247, 4293, 15619, 15619, 4293, 247, 1, 0, 1, 502, 14608, 88234, 156190, 88234, 14608, 502, 1, 0, 1, 1013, 47840, 455192, 1310354, 1310354, 455192, 47840, 1013, 1, 0
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OFFSET
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0,8
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COMMENTS
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This version indexes the Eulerian numbers in the same way as Graham et al.'s Concrete Mathematics (see references section). The traditional indexing, used by Riordan, Comtet and others, is given in A008292, which is the main entry for the Eulerian numbers.
Triangle T(n,k), read by rows, given by [1,0,2,0,3,0,4,0,5,0,6,0,7,0,8,0,9,...] DELTA [0,1,0,2,0,3,0,4,0,5,0,6,0,7,0,8,0,9,...] where DELTA is the operator defined in A084938. - Philippe Deléham Sep 30 2011
[ E(.,t)/(1-t)]^n = n!*Lag[n,-P(.,t)/(1-t)] and [ -P(.,t)/(1-t)]^n = n!*Lag[n, E(.,t)/(1-t)] umbrally comprise a combinatorial Laguerre transform pair, where E(n,t) are the Eulerian polynomials (e.g., E(2,t)= 1+t) and P(n,t) are the polynomials related to polylogarithms in A131758. - Tom Copeland, Oct 03 2014
See A131758 for connections of the evaluation of these polynomials at -1 (alternating row sum) to the Euler, Genocchi, Bernoulli, and zag/tangent numbers and values of the Riemann zeta function and polylogarithms. See also A119879 for the Swiss-knife polynomials. - Tom Copeland, Oct 20 2015
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REFERENCES
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R. L. Graham, D. E. Knuth and O. Patashnik, Concrete Mathematics. Addison-Wesley, Reading, MA, 1990, table 254.
See A008292 for additional references and links.
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LINKS
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FORMULA
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T(n, k) = Sum_{j=0..k} (-1)^j*binomial(n+1, j)*(k+1-j)^n. - G. C. Greubel, Feb 25 2019
T(n, k) = (-1)^n*(n+1)!*[x^k][t^n](1 + log((x*exp(-t) - exp(-t*x))/(x-1))/(t*x)). - Peter Luschny, Aug 12 2022
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EXAMPLE
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Triangle begins:
[ 0] 1,
[ 1] 1, 0,
[ 2] 1, 1, 0,
[ 3] 1, 4, 1, 0,
[ 4] 1, 11, 11, 1, 0,
[ 5] 1, 26, 66, 26, 1, 0,
[ 6] 1, 57, 302, 302, 57, 1, 0,
[ 7] 1, 120, 1191, 2416, 1191, 120, 1, 0,
[ 8] 1, 247, 4293, 15619, 15619, 4293, 247, 1, 0,
[ 9] 1, 502, 14608, 88234, 156190, 88234, 14608, 502, 1, 0,
[10] 1, 1013, 47840, 455192, 1310354, 1310354, 455192, 47840, 1013, 1, 0.
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MAPLE
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T:= proc(n, k) option remember;
if k=0 and n>=0 then 1
elif k<0 or k>n then 0
else (n-k) * T(n-1, k-1) + (k+1) * T(n-1, k)
fi
end:
# Maple since version 13:
# Or:
egf := 1 + log((x*exp(-t) - exp(-t*x))/(x-1))/(t*x):
ser := series(egf, t, 12): ct := n -> coeff(ser, t, n):
seq(print(seq((-1)^n*(n+1)!*coeff(ct(n), x, k), k=0..n)), n=0..8); # Peter Luschny, Aug 12 2022
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MATHEMATICA
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t[n_ /; n >= 0, 0] = 1; t[n_, k_] /; k < 0 || k > n = 0;
t[n_, k_] := t[n, k] = (n-k)*t[n-1, k-1] + (k+1)*t[n-1, k]; Flatten[Table[t[n, k], {n, 0, 11}, {k, 0, n}]][[1 ;; 60]]
<< Combinatorica`
Flatten[Table[Eulerian[n, k], {n, 0, 20}, {k, 0, n}]]
(* To generate the table of the numbers T(n, k) *)
RecurrenceTable[{T[n + 1, k + 1] == (n - k) T[n, k] + (k + 2) T[n, k + 1], T[0, k] == KroneckerDelta[k]}, T, {n, 0, 12}, {k, 0, 12}] (* Emanuele Munarini, Jan 03 2018 *)
Table[If[n==0, 1, Sum[(-1)^j*Binomial[n+1, j]*(k+1-j)^n, {j, 0, k+1}]], {n, 0, 12}, {k, 0, n}]//Flatten (* G. C. Greubel, Feb 25 2019 *)
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PROG
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(Sage)
@CachedFunction
def eulerian1(n, k):
if k==0: return 1
if k==n: return 0
return eulerian1(n-1, k)*(k+1)+eulerian1(n-1, k-1)*(n-k)
for n in (0..9): [eulerian1(n, k) for k in(0..n)] # Peter Luschny, Nov 11 2012
(Sage) [1] + [[sum((-1)^(k-j+1)*binomial(n+1, k-j+1)*j^n for j in (0..k+1)) for k in (0..n)] for n in (1..12)] # G. C. Greubel, Feb 25 2019
(Haskell)
a173018 n k = a173018_tabl !! n !! k
a173018_row n = a173018_tabl !! n
a173018_tabl = map reverse a123125_tabl
(Magma) [[n le 0 select 1 else (&+[(-1)^j*Binomial(n+1, j)*(k-j+1)^n: j in [0..k+1]]): k in [0..n]]: n in [0..12]]; // G. C. Greubel, Feb 25 2019
(PARI) T(n, k) = if(n==0, 1, sum(j=0, k+1, (-1)^(k-j+1)*binomial(n+1, k-j+1)*j^n)); \\ G. C. Greubel, Feb 28 2020
(Magma) T:= func< n, k | n eq 0 select 1 else &+[(-1)^(k-j+1)*Binomial(n+1, k-j+1)*j^n: j in [0..k+1]] >;
[T(n, k): k in [0..n], n in [0..12]]; // G. C. Greubel, Feb 28 2020
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CROSSREFS
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Cf. A123125 (row reversed version).
For this triangle read mod m for m=2 through 10 see A290452-A290460. See also A047999 for the mod 2 version.
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KEYWORD
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AUTHOR
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STATUS
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approved
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