A115520 Number of ordered triples (i,j,k) in range [0..n] satisfying i == j mod 2 and j == k mod 3.

1, 2, 5, 12, 23, 36, 61, 88, 123, 170, 227, 288, 373, 462, 565, 688, 827, 972, 1153, 1340, 1547, 1782, 2039, 2304, 2617, 2938, 3285, 3668, 4079, 4500, 4981, 5472, 5995, 6562, 7163, 7776, 8461, 9158, 9893, 10680, 11507, 12348, 13273, 14212, 15195, 16238, 17327, 18432, 19633

Offset: 0

Author

N. J. A. Sloane and Vinay Vaishampayan, Mar 09 2006

Keywords

• nonn

Crossrefs

Cf. A115523.

Formula

a(n) = binomial(n+1,3) - linear (PORC) correction term which depends on n mod 6.