A095894 a(2n) = 6*n^2 + 7*n + 1; a(2n+1) = 6*n^2 + 13*n + 7.

1, 7, 14, 26, 39, 57, 76, 100, 125, 155, 186, 222, 259, 301, 344, 392, 441, 495, 550, 610, 671, 737, 804, 876, 949, 1027, 1106, 1190, 1275, 1365, 1456, 1552, 1649, 1751, 1854, 1962, 2071, 2185, 2300, 2420, 2541, 2667, 2794, 2926, 3059, 3197, 3336, 3480

Offset

0,2

Comments

From Omar E. Pol, Jul 18 2012: (Start)

Positive terms of A051866 and positive terms of A049453 interleaved.

Also sequence found by reading the line from 1, in the direction 1, 14, ..., and the line from 7, in the direction 7, 26, ..., in the square spiral whose vertices are the generalized pentagonal numbers A001318. (End)

Links

G. C. Greubel, Table of n, a(n) for n = 0..1000

Index entries for linear recurrences with constant coefficients, signature (2,0,-2,1).

Formula

G.f.: ( -1-5*x ) / ( (1+x)*(x-1)^3 ). - R. J. Mathar, Oct 26 2011

Mathematica

LinearRecurrence[{2, 0, -2, 1}, {1, 7, 14, 26}, 60] (* Harvey P. Dale, Oct 13 2016 *)

Prog

(PARI) x='x+O('x^50); Vec((-1-5*x)/((1+x)*(x-1)^3)) \\ G. C. Greubel, Jun 19 2017

Crossrefs

Cf. A047225 (first differences), A049453, A051866.

Sequence in context: A232871 A232854 A232790 * A104599 A115874 A083495

Adjacent sequences: A095891 A095892 A095893 * A095895 A095896 A095897

Keyword

nonn,easy

Author

Gary W. Adamson, Jun 11 2004

Extensions

Edited by Don Reble, Nov 16 2005

Status

approved