A363268 Squares (A000290) alternating with 1+squares (A002522).

1, 1, 4, 2, 9, 5, 16, 10, 25, 17, 36, 26, 49, 37, 64, 50, 81, 65, 100, 82, 121, 101, 144, 122, 169, 145, 196, 170, 225, 197, 256, 226, 289, 257, 324, 290, 361, 325, 400, 362, 441, 401, 484, 442, 529, 485, 576, 530, 625, 577, 676, 626, 729, 677, 784, 730, 841

Offset

1,3

Links

Table of n, a(n) for n=1..57.

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

Formula

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

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

Mathematica

c[1] = 1; c[2] = 1;
c[n_] := If[OddQ[n], c[n - 2] + n, c[n - 1] - n + 2]
Table[c[n], {n, 1, 120}]

Crossrefs

Cf. A000290, A002522, A123596, A363267, A363269, A363283.

Sequence in context: A365378 A289506 A373710 * A213778 A095833 A163990

Adjacent sequences: A363265 A363266 A363267 * A363269 A363270 A363271

Keyword

nonn,easy

Author

Clark Kimberling, May 24 2023

Status

approved