A064070 Generalized Euler number c(9,n).

2, 126, 49410, 48649086, 89434106370, 264235243691646, 1145011717430672130, 6841110155700330881406, 53899295662946509072626690, 541439307193573593050370186366, 6754273504043546592593642328610050, 102439130403410639137159601119206854526

Offset

0,1

Links

Table of n, a(n) for n=0..11.

D. Shanks, Generalized Euler and class numbers. Math. Comp. 21 (1967) 689-694.

D. Shanks, Corrigenda to: "Generalized Euler and class numbers", Math. Comp. 22 (1968), 699.

Eric Weisstein's World of Mathematics, Euler Number.

Formula

a(n) = (2*n)!*[x^(2*n)](sec(9*x)*2*cos(3*x)^2). - Peter Luschny, Nov 21 2021

Maple

egf := sec(9*x)*2*cos(3*x)^2: ser := series(egf, x, 24):
seq((2*n)!*coeff(ser, x, 2*n), n = 0..10); # Peter Luschny, Nov 21 2021

Crossrefs

Cf. A064074, A349268, A349264.

Sequence in context: A237994 A348159 A157070 * A266993 A364654 A139904

Adjacent sequences: A064067 A064068 A064069 * A064071 A064072 A064073

Keyword

nonn,easy

Author

Eric W. Weisstein, Aug 31 2001

Status

approved