OFFSET
1,2
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 1..300
FORMULA
a(n) = ((n-1)*(2n+1)^n + 1)/n.
PROG
(Magma) [((n-1)*(2*n+1)^n+1)/n: n in [1..20]]; // Vincenzo Librandi, Nov 12 2011
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Paul Barry, Apr 23 2003
STATUS
approved