A348228 Partial sums of A348227.

1, 5, 17, 37, 71, 109, 163, 217, 291, 361, 455, 541, 655, 757, 891, 1009, 1163, 1297, 1471, 1621, 1815, 1981, 2195, 2377, 2611, 2809, 3063, 3277, 3551, 3781, 4075, 4321, 4635, 4897, 5231, 5509, 5863, 6157, 6531, 6841, 7235, 7561, 7975, 8317, 8751, 9109, 9563, 9937, 10411

Offset

0,2

Links

Alois P. Heinz, Table of n, a(n) for n = 0..10000

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

Formula

See A348227 for G.f.

a(n) = (18*n^2 + 2*n - 17 + (2*n - 3)*(-1)^n)/4 for n >= 3. - Charles R Greathouse IV, May 31 2026

a(n) ~ 9*n^2/2. - Charles R Greathouse IV, May 31 2026

Mathematica

LinearRecurrence[{1, 2, -2, -1, 1}, {1, 5, 17, 37, 71, 109, 163, 217}, 100] (* Paolo Xausa, Feb 28 2024 *)

Prog

(PARI) a(n)=if(n>2, (9*n^2+(2-n%2*2)*n+-10+n%2*3)/2, [1, 5, 17][n+1]) \\ Charles R Greathouse IV, May 31 2026

Crossrefs

Cf. A348227.

Sequence in context: A162373 A146781 A338277 * A107199 A383925 A048209

Adjacent sequences: A348225 A348226 A348227 * A348229 A348230 A348231

Keyword

nonn,easy

Author

N. J. A. Sloane, Oct 08 2021

Status

approved