OFFSET
1,2
COMMENTS
a(1) = 1, a(n+1) = sum of a(n) numbers beginning with a(n) + 1: a(2) = 2, a(3) = 3+4 = 7, a(4) = 8+9+...13+14 = 77. - Amarnath Murthy, Sep 07 2005
LINKS
Harry J. Smith, Table of n, a(n) for n = 1..12
FORMULA
EXAMPLE
a(3) = 7 so a(4) = 7*(3*7 + 1)/2 = 7*22/2 = 77.
MATHEMATICA
f[n_Integer] := n(3n + 1)/2; NestList[f, 2, 8]
PROG
(PARI) { a=2/3; for (n = 1, 12, write("b059406.txt", n, " ", a=a*(3*a + 1)/2); ) } \\ Harry J. Smith, Jun 26 2009
CROSSREFS
KEYWORD
nonn
AUTHOR
Robert G. Wilson v, Jan 29 2001
STATUS
approved