OFFSET
1,6
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..1000
FORMULA
G.f.: Product_{j>=1} (1 + x^(2*(2^j-1))/(1-x^(2^j-1))). - Emeric Deutsch, Jun 28 2009
EXAMPLE
a(16)=5 because we have 7711, 33331111, 3331^7, 331^(10), and 1^(16). - Emeric Deutsch, Jun 28 2009
MAPLE
g := product(1+x^(2*(2^j-1))/(1-x^(2^j-1)), j = 1 .. 20): gser := series(g, x = 0, 80): seq(coeff(gser, x, n), n = 1 .. 74); # Emeric Deutsch, Jun 28 2009
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Jun 02 2009
STATUS
approved