A361556 Central terms of triangle A361550.

1, 5, 61, 1660, 47460, 1621116, 58002140, 2213389940, 87301563690, 3555890156445, 148125509781095, 6292884402884976, 271565202254735207, 11878392121526009800, 525519782174930309205, 23481280252471520720288, 1058270749214634093475910, 48058678036035725619136698

Offset

0,2

Links

Paul D. Hanna, Table of n, a(n) for n = 0..50

Formula

a(n) = A361550(2*n,n) for n >= 0.

a(n) ~ c * d^n / n^2, where d = 51.1751... and c = 0.12624... - Vaclav Kotesovec, Mar 19 2023

Prog

(PARI) {A361550(n, k) = my(A=[1]); for(i=1, n, A = concat(A, 0);
A[#A] = polcoeff(x*y - prod(m=1, #A, (1 - x^m) * (1 - x^m*Ser(A)) * (1 - x^(m-1)/Ser(A)) * (1 - x^(2*m-1)*Ser(A)^2) * (1 - x^(2*m-1)/Ser(A)^2) ), #A-1) );
polcoeff(polcoeff(Ser(A), n, x), k, y)}
for(n=0, 20, print1(A361550(2*n, n), ", "))

Crossrefs

Cf. A361550.

Sequence in context: A000364 A028296 A159316 * A231798 A258672 A326571

Adjacent sequences: A361553 A361554 A361555 * A361557 A361558 A361559

Keyword

nonn

Author

Paul D. Hanna, Mar 19 2023

Status

approved