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 A239005 Signed version of the Seidel triangle for the Euler numbers, read by rows. 5

%I

%S 1,0,1,-1,-1,0,0,-1,-2,-2,5,5,4,2,0,0,5,10,14,16,16,-61,-61,-56,-46,

%T -32,-16,0,0,-61,-122,-178,-224,-256,-272,-272,1385,1385,1324,1202,

%U 1024,800,544,272,0,0,1385,2770,4094,5296,6320,7120,7664,7936,7936

%N Signed version of the Seidel triangle for the Euler numbers, read by rows.

%H L. Seidel, <a href="http://publikationen.badw.de/de/003384831/pdf/CC%20BY">Über eine einfache Entstehungsweise der Bernoullischen Zahlen und einiger verwandten Reihen</a>, Sitzungsberichte der mathematisch-physikalischen Classe der königlich bayerischen Akademie der Wissenschaften zu München, Vol. 7 (1877), pp. 157-187; see Beilage 4 (p. 187).

%F a(n) = A057077(n)*A008280(n) by rows.

%F a(n) is the increasing antidiagonals of the difference table of A155585(n).

%F Central column of triangle: A099023(n).

%F Right main diagonal of triangle: A155585(n) (see A009006(n)).

%F Left main diagonal of triangle: A122045(n).

%F T(n,m) = Sum_{k=0..n} binomial(m,k)*Euler(n-m+k) for 0 <= m <= n. - _Vladimir Kruchinin_, Apr 06 2015 [The summation only needs to go from k=0 to k=m because of binomial(m,k).]

%F T(n,k) = (-1)^n*A236935(n-k,k) for 0 <= k <= n, where the latter is read as a square array. - _Petros Hadjicostas_, Feb 21 2021

%e The triangle T(n,k) begins:

%e 1

%e 0 1

%e -1 -1 0

%e 0 -1 -2 -2

%e 5 5 4 2 0

%e ...

%e The array read as a table, A(n,k) = T(n+k, k), starts:

%e 1, 1, 0, -2, 0, 16, 0, -272, 0, ...

%e 0, -1, -2, 2, 16, -16, -272, 272, ...

%e -1, -1, 4, 14, -32, -256, 544, ...

%e 0, 5, 10, -46, -224, 800, ...

%e 5, 5, -56, -178, 1024, ...

%e 0, -61, -122, 1202, ...

%e -61, -61, 1324, ...

%e 0, 1385, ...

%e 1385, ...

%e ...

%e For the above table, we have A(n,k) = (-1)^(n+k)*A236935(n,k) for n, k >= 0. It has joint e.g.f. 2*exp(-x)/(1 + exp(-2*(x+y))). - _Petros Hadjicostas_, Feb 21 2021

%t t[0, 0] = 1; t[n_, m_] /; n<m || m<0 = 0; t[n_, m_] := t[n, m] = Sum[t[n-1, n-k], {k, m}]; Table[r = (-1)^Floor[n/2]*Table[t[n, m], {m, 0, n}]; If[EvenQ[n], Reverse[r], r], {n, 0, 9}] // Flatten (* _Jean-François Alcover_, Dec 30 2014 *)

%o (Maxima)

%o T(n,m):=sum(binomial(m,k)*euler(n-m+k),k,0,m); /* _Vladimir Kruchinin_, Apr 06 2015 */

%o (PARI) a(n) = 2^n*2^(n+1)*(subst(bernpol(n+1, x), x, 3/4) - subst(bernpol(n+1, x), x, 1/4))/(n+1) /* A122045 */

%o T(n, k) = (-1)^n*sum(i=0, k, (-1)^i*binomial(k, i)*a(n-i)) /* _Petros Hadjicostas_, Feb 21 2021 */

%o /* Second PARI program (same a(n) for A122045 as above) */

%o T(n, k) = sum(i=0, k, binomial(k, i)*a(n-k+i)) /* _Petros Hadjicostas_, Feb 21 2021 */

%Y Unsigned version is A008280.

%Y Cf. A008281, A099023, A108040, A122045, A155585, A236935.

%K sign,tabl

%O 0,9

%A _Paul Curtz_, Mar 08 2014

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Last modified July 24 01:41 EDT 2021. Contains 346269 sequences. (Running on oeis4.)