A139595 A139277(n) followed by A139273(n+1).

0, 5, 13, 26, 42, 63, 87, 116, 148, 185, 225, 270, 318, 371, 427, 488, 552, 621, 693, 770, 850, 935, 1023, 1116, 1212, 1313, 1417, 1526, 1638, 1755, 1875, 2000, 2128, 2261, 2397, 2538, 2682, 2831, 2983, 3140, 3300, 3465, 3633, 3806

Offset

0,2

Comments

Sequence found by reading the line from 0, in the direction 0, 5,... and the same line from 0, in the direction 0, 13,..., in the square spiral whose vertices are the triangular numbers A000217.

Links

Table of n, a(n) for n=0..43.

Omar E. Pol, Determinacion geometrica de los numeros primos y perfectos.

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

Formula

Array read by rows: row n gives 8*n^2 + 5n, 8*(n+1)^2 - 3(n+1).

G.f.: -x*(5+3*x) / ( (1+x)*(x-1)^3 ). - R. J. Mathar, Feb 13 2011

Example

Array begins:
0, 5
13, 26
42, 63
87, 116

Mathematica

LinearRecurrence[{2, 0, -2, 1}, {0, 5, 13, 26}, 50] (* Harvey P. Dale, Jul 31 2021 *)

Crossrefs

Cf. A000217, A046092, A139273, A139277, A077221, A139591, A139592, A139593, A139596, A139597, A139598.

Sequence in context: A173979 A190446 A188471 * A301673 A301300 A301677

Adjacent sequences: A139592 A139593 A139594 * A139596 A139597 A139598

Keyword

easy,nonn

Author

Omar E. Pol, May 03 2008

Status

approved