A007981 Number of nonsplit type 2 metacyclic 2-groups of order 2^n.

0, 0, 0, 0, 0, 0, 0, 1, 2, 4, 6, 10, 13, 19, 24, 32, 39, 50, 59, 73, 85, 102, 117, 138, 156, 181, 203, 232, 258, 292, 322, 361, 396, 440, 480, 530, 575, 631, 682, 744, 801, 870, 933, 1009, 1079, 1162, 1239, 1330, 1414, 1513, 1605, 1712, 1812, 1928, 2036, 2161

Offset

1,9

Comments

See Theorem 5 of Liedahl. - Eric M. Schmidt, Jan 09 2015

Links

Colin Barker, Table of n, a(n) for n = 1..1000

Steven Liedahl, Enumeration of metacyclic p-groups, J. Algebra 186 (1996), no. 2, 436-446.

Index entries for linear recurrences with constant coefficients, signature (1,2,-1,-2,-1,2,1,-1).

Formula

G.f.: -x^8*(x^3-x-1) / ((x-1)^4*(x+1)^2*(x^2+x+1)). - Colin Barker, Jan 12 2015

Prog

(PARI) concat([0, 0, 0, 0, 0, 0, 0], Vec(-x^8*(x^3-x-1)/((x-1)^4*(x+1)^2*(x^2+x+1)) + O(x^100))) \\ Colin Barker, Jan 12 2015

Crossrefs

Sequence in context: A365321 A267452 A140652 * A258847 A238627 A336415

Adjacent sequences: A007978 A007979 A007980 * A007982 A007983 A007984

Keyword

nonn,easy

Author

S. Liedahl

Extensions

More terms and initial zeros from Eric M. Schmidt, Jan 11 2015

Status

approved