OFFSET
1,2
LINKS
Alois P. Heinz, Table of n, a(n) for n = 1..1000
Knopfmacher, Arnold; Munagi, Augustine O. Smallest parts in compositions, Kotsireas, Ilias S. (ed.) et al., Advances in combinatorics. 3rd Waterloo workshop on computer algebra (WWCA, W80) 2011, Waterloo, Canada, May 26-29, 2011. Berlin: Springer. 197-207 (2013).
FORMULA
G.f.: (1-x)^2 * Sum_{k>=1} k*x^k/(1-x-x^k)^2.
a(n) ~ n * 2^(n-3). - Vaclav Kotesovec, Sep 05 2014
a(n) = Sum_{k=1..n} A308630(n,k). - R. J. Mathar, Jun 12 2019
MATHEMATICA
Drop[ CoefficientList[ Series[(1 - x)^2*Sum[k*x^k/(1 - x - x^k)^2, {k, 50}], {x, 0, 30}], x], 1] (* Robert G. Wilson v, Sep 08 2004 *)
CROSSREFS
KEYWORD
easy,nonn,changed
AUTHOR
Vladeta Jovovic, Sep 05 2004
EXTENSIONS
More terms from Robert G. Wilson v, Sep 08 2004
STATUS
approved