OFFSET
1,1
COMMENTS
Intersection of A000566 and A193866 (even pentagonal numbers divided by 2). - Michel Marcus, Jun 20 2015
LINKS
Colin Barker, Table of n, a(n) for n = 1..186
Index entries for linear recurrences with constant coefficients, signature (232323,-232323,1).
FORMULA
G.f.: -x*(x^2+28015*x+540) / ((x-1)*(x^2-232322*x+1)).
EXAMPLE
540 is in the sequence because 540 is the 15th heptagonal number, and 2*540 is the 27th pentagonal number.
MATHEMATICA
LinearRecurrence[{232323, -232323, 1}, {540, 125482435, 29152330292086}, 20] (* Vincenzo Librandi, Jun 20 2015 *)
PROG
(PARI) Vec(-x*(x^2+28015*x+540)/((x-1)*(x^2-232322*x+1)) + O(x^20))
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Colin Barker, Jun 19 2015
STATUS
approved