OFFSET
0,2
REFERENCES
"Supplemento al Periodico di Matematica", Raffaello Giusti Editore (Livorno), Apr/May 1913 p. 99 (Problem 1277, case x=n).
LINKS
Bruno Berselli, Table of n, a(n) for n = 0..300
FORMULA
a(n) = (n+1)*(4*n^(n+1)-3*n^(n+2)-n^(n+3)+n^(n+4)-1)/(n-1)^3 for n>1; a(0)=1, a(1)=5.
EXAMPLE
a(4) = 7585 because 7585 = 1+2^2*4+3^2*4^2+4^2*4^3+5^2*4^4.
MATHEMATICA
Join[{1, 5}, Table[(n + 1) (4 n^(n + 1) - 3 n^(n + 2) - n^(n + 3) + n^(n + 4) -1) / (n - 1)^3, {n, 2, 20}]] (* Vincenzo Librandi, Aug 19 2013 *)
PROG
(Magma) [&+[(k+1)^2*n^k: k in [0..n]]: n in [0..17]];
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Bruno Berselli, Apr 19 2011
STATUS
approved