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A139595
A139277(n) followed by A139273(n+1).
6
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.
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 *)
KEYWORD
easy,nonn
AUTHOR
Omar E. Pol, May 03 2008
STATUS
approved