A023551 Self-convolution of natural numbers >= 3.

9, 24, 46, 76, 115, 164, 224, 296, 381, 480, 594, 724, 871, 1036, 1220, 1424, 1649, 1896, 2166, 2460, 2779, 3124, 3496, 3896, 4325, 4784, 5274, 5796, 6351, 6940, 7564, 8224, 8921, 9656, 10430, 11244, 12099, 12996, 13936, 14920, 15949

Offset: 1

Author

Clark Kimberling

Keywords

• nonn
• easy

Links

• Vincenzo Librandi, Table of n, a(n) for n = 1..10000
• Index entries for linear recurrences with constant coefficients, signature (4,-6,4,-1).

Programs

Magma

[n*(n^2+15*n+38)/6: n in [1..50]]; // Vincenzo Librandi, Oct 22 2011

PARI

a(n) = n*(n^2+15*n+38)/6 \\ Charles R Greathouse IV, Oct 21 2011

Formula

a(n) = n*(n^2 + 15*n + 38)/6. - Robert Lester (RobertLester(AT)Earthlink.net), Jan 31 2005

G.f.: x*(3-2*x)^2/(1-x)^4. - Bruno Berselli, Oct 21 2011