A047668 Row 4 of array in A047666.

4, 17, 52, 129, 276, 529, 932, 1537, 2404, 3601, 5204, 7297, 9972, 13329, 17476, 22529, 28612, 35857, 44404, 54401, 66004, 79377, 94692, 112129, 131876, 154129, 179092, 206977, 238004, 272401, 310404, 352257, 398212, 448529

Offset: 1

Author

N. J. A. Sloane

Keywords

• nonn

Comments

In this sequence if we do a forward difference, then the 3rd forward difference when considered as a sequence will be an arithmetic progression with common difference 8. [Gopalakrishnan (gopala498(AT)yahoo.co.in), Jun 05 2010]

Links

• Index entries for linear recurrences with constant coefficients, signature (5, -10, 10, -5, 1).

Programs

Mathematica

LinearRecurrence[{5,-10,10,-5,1},{4,17,52,129,276},40] (* Harvey P. Dale, Jul 05 2024 *)

Formula

a(n) = (1/3) * (n^4 + 8n^2 + 3).

G.f.: x*(4 - 3*x + 7*x^2 - x^3 + x^4)/(1-x)^5. - Maksym Voznyy (voznyy(AT)mail.ru), Jul 27 2009 [corrected by R. J. Mathar, Sep 16 2009]