OFFSET
1,1
COMMENTS
The natural numbers of the form 5*n^2-1, with n odd. See also A158491 for the cases where n is even. - Giovanni Teofilatto, Oct 10 2011
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 1..10000
Index entries for linear recurrences with constant coefficients, signature (3,-3,1).
FORMULA
a(n) = 4*A062786(n).
G.f.: -4*x*(1+8*x+x^2) / (x-1)^3. - R. J. Mathar, Aug 26 2011
a(n) = 3*a(n-1)-3*a(n-2)+a(n-3) for n>3. - Wesley Ivan Hurt, Nov 21 2015
MAPLE
MATHEMATICA
Table[4*(5*n^2 - 5*n + 1), {n, 50}] (* Wesley Ivan Hurt, Nov 21 2015 *)
PROG
(Magma) [4*(5*n^2-5*n+1): n in [1..50]]; // Vincenzo Librandi, Aug 30 2011
(PARI) a(n) = 4*(5*n^2 - 5*n + 1) \\ Anders Hellström, Nov 21 2015
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Giovanni Teofilatto, Jul 26 2011
STATUS
approved