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
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
KEYWORD
easy,nonn
AUTHOR
Omar E. Pol, May 03 2008
STATUS
approved