OFFSET
1,4
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
a(n) = A136185(n) - floor(n/2) - 1. - Eric M. Schmidt, Jan 08 2015
G.f.: -x^3*(x^4-x-1) / ((x-1)^4*(x+1)^2*(x^2+x+1)). - Colin Barker, Jan 12 2015
MATHEMATICA
LinearRecurrence[{1, 2, -1, -2, -1, 2, 1, -1}, {0, 0, 1, 2, 4, 7, 10, 15}, 60] (* Harvey P. Dale, Jun 17 2016 *)
PROG
(PARI) concat([0, 0], Vec(-x^3*(x^4-x-1)/((x-1)^4*(x+1)^2*(x^2+x+1)) + O(x^100))) \\ Colin Barker, Jan 12 2015
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
S. Liedahl
EXTENSIONS
Initial terms added and sequence extended (using A136185) by Eric M. Schmidt, Jan 08 2015
STATUS
approved