A106389 Numbers j such that 6j^2 + 6j + 1 = 13k.

1, 11, 14, 24, 27, 37, 40, 50, 53, 63, 66, 76, 79, 89, 92, 102, 105, 115, 118, 128, 131, 141, 144, 154, 157, 167, 170, 180, 183, 193, 196, 206, 209, 219, 222, 232, 235, 245, 248, 258, 261, 271, 274, 284, 287, 297, 300, 310, 313, 323, 326, 336, 339, 349, 352

Offset: 1

Author

Pierre CAMI, May 01 2005

Keywords

• nonn
• easy

Links

• Harvey P. Dale, Table of n, a(n) for n = 1..1000
• Index entries for linear recurrences with constant coefficients, signature (1,1,-1).

Crossrefs

Cf. A106387, A106388, A106390.

For k sequence see A106390.

Programs

Mathematica

fQ[n_] := IntegerQ[(6n(n + 1) + 1)/13]; Select[ Range[ 361], fQ[ # ] &] (* Robert G. Wilson v, May 02 2005 *)
LinearRecurrence[{1,1,-1},{1,11,14},60] (* Harvey P. Dale, Jun 07 2016 *)

PARI

Vec((2*x^2+10*x+1)/((x-1)^2*(x+1)) + O(x^100)) \\ Colin Barker, Apr 16 2014

Formula

j(1)=1, j(2)=11; then j(n)=j(n-2)+13.

a(n) = (-15+7*(-1)^n+26*n)/4. G.f.: x*(2*x^2+10*x+1) / ((x-1)^2*(x+1)). - Colin Barker, Apr 16 2014

Extensions

More terms from Robert G. Wilson v, May 02 2005