A179337 Positive integers of the form (6*m^2 + 1)/11.

5, 35, 107, 197, 341, 491, 707, 917, 1205, 1475, 1835, 2165, 2597, 2987, 3491, 3941, 4517, 5027, 5675, 6245, 6965, 7595, 8387, 9077, 9941, 10691, 11627, 12437, 13445, 14315, 15395, 16325, 17477, 18467, 19691, 20741, 22037, 23147, 24515

Offset: 1

Author

Bruno Berselli, Jul 11 2010

Keywords

• nonn
• easy

Comments

Here m = (11*(2*n-1) - (-1)^n)/4 for n > 0.

Links

• B. Berselli, Table of n, a(n) for n = 1..10000.
• Index entries for linear recurrences with constant coefficients, signature (1,2,-2,-1,1).

Crossrefs

Cf. A113338, A179088, A179338, A179339, A179370.

Programs

Magma

[(66*n*(n-1)-3*(2*n-1)*(-1)^n+17)/4: n in [1..40]]; // Vincenzo Librandi, Nov 16 2011

Mathematica

LinearRecurrence[{1,2,-2,-1,1},{5,35,107,197,341},40] (* Vincenzo Librandi, Nov 16 2011 *)

Formula

a(n) = (66*n*(n-1) - 3*(2*n-1)*(-1)^n + 17)/4.

G.f.: x*(5 + 30*x + 62*x^2 + 30*x^3 + 5*x^4)/((1+x)^2*(1-x)^3).

a(n) = a(-n+1) = a(n-1) + 2*a(n-2) - 2*a(n-3) - a(n-4) + a(n-5).