A179902 Row sums of triangle A179901.

1, 2, 5, 11, 23, 46, 87, 155, 261, 418, 641, 947, 1355, 1886, 2563, 3411, 4457, 5730, 7261, 9083, 11231, 13742, 16655, 20011, 23853, 28226, 33177, 38755, 45011, 51998, 59771, 68387, 77905, 88386, 99893, 112491, 126247, 141230, 157511, 175163, 194261, 214882

Offset

1,2

Comments

Conjectured mod 2 parity: (1, 0, 1, 1, 1, 0, 1, 1, 1, 0, 1, 1, 1,...).

Links

Andrew Howroyd, Table of n, a(n) for n = 1..1000

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

Formula

a(n) = (n^4 - 8*n^3 + 35*n^2 - 52*n + 36)/12. - Andrew Howroyd, Sep 21 2025

From Elmo R. Oliveira, May 25 2026: (Start)

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

E.g.f.: (1/12)*exp(x)*(x^4 - 2*x^3 + 18*x^2 - 24*x + 36) - 3.

a(n) = 5*a(n-1) - 10*a(n-2) + 10*a(n-3) - 5*a(n-4) + a(n-5). (End)

Example

a(5) = 23 = 1 + 4 + 6 + 8 + 4 = sum of row 5 of triangle A179901.

Crossrefs

Cf. A179901.

Sequence in context: A333396 A277828 A147878 * A140992 A248646 A383472

Adjacent sequences: A179899 A179900 A179901 * A179903 A179904 A179905

Keyword

nonn,easy

Author

Gary W. Adamson, Jul 31 2010

Extensions

a(10) corrected and a(15) onwards from Andrew Howroyd, Sep 21 2025

Status

approved