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A144042
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Square array A(n,k), n>=1, k>=1, read by antidiagonals, with A(1,k)=1 and sequence a_k of column k shifts left when Euler transform applied k times.
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12
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1, 1, 1, 1, 1, 2, 1, 1, 3, 4, 1, 1, 4, 8, 9, 1, 1, 5, 13, 25, 20, 1, 1, 6, 19, 51, 77, 48, 1, 1, 7, 26, 89, 197, 258, 115, 1, 1, 8, 34, 141, 410, 828, 871, 286, 1, 1, 9, 43, 209, 751, 2052, 3526, 3049, 719, 1, 1, 10, 53, 295, 1260, 4337, 10440, 15538, 10834, 1842, 1, 1, 11, 64
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refs;
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OFFSET
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1,6
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LINKS
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M. Bernstein and N. J. A. Sloane, Some canonical sequences of integers, Linear Alg. Applications, 226-228 (1995), 57-72; erratum 320 (2000), 210. [Link to Lin. Alg. Applic. version together with omitted figures]
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EXAMPLE
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Square array begins:
1, 1, 1, 1, 1, 1, 1, 1, ...
1, 1, 1, 1, 1, 1, 1, 1, ...
2, 3, 4, 5, 6, 7, 8, 9, ...
4, 8, 13, 19, 26, 34, 43, 53, ...
9, 25, 51, 89, 141, 209, 295, 401, ...
20, 77, 197, 410, 751, 1260, 1982, 2967, ...
48, 258, 828, 2052, 4337, 8219, 14379, 23659, ...
115, 871, 3526, 10440, 25512, 54677, 106464, 192615, ...
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MAPLE
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etr:= proc(p) local b; b:= proc(n) option remember; `if`(n=0, 1,
add(add(d*p(d), d=numtheory[divisors](j))*b(n-j), j=1..n)/n)
end end:
g:= proc(k) option remember; local b, t; b[0]:= j->
`if`(j<2, j, b[k](j-1)); for t to k do
b[t]:= etr(b[t-1]) od: eval(b[0])
end:
A:= (n, k)-> g(k)(n):
seq(seq(A(n, 1+d-n), n=1..d), d=1..14); # revised Alois P. Heinz, Aug 27 2018
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MATHEMATICA
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etr[p_] := Module[{b}, b[n_] := b[n] = Module[{d, j}, If[n == 0, 1, Sum[Sum[d*p[d], {d, Divisors[j]}]*b[n-j], {j, 1, n}]/n]]; b]; A[n_, k_] := Module[{a, b, t}, b[1] = etr[a]; For[t = 2, t <= k, t++, b[t] = etr[b[t-1]]]; a = Function[m, If[m == 1, 1, b[k][m-1]]]; a[n]]; Table[Table[A[n, 1 + d-n], {n, 1, d}], {d, 1, 14}] // Flatten (* Jean-François Alcover, Dec 20 2013, translated from Maple *)
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CROSSREFS
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KEYWORD
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AUTHOR
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STATUS
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approved
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