OFFSET
0,3
FORMULA
(1 + x + 3x^2 + 6x^3 + 12x^4 + ...) = (1 + x + 2x^2 + 3x^3 + 5x^4 + ...) *
(1 + x^2 + 2x^3 + 3x^4 + 5x^5 + ...); given A000041 = (1, 1, 2, 3, 5, 7, ...).
EXAMPLE
a(5) = 22 = (7, 5, 3, 2, 1, 1) dot (1, 0, 1, 2, 3, 5) = (7 + 0 + 3 + 4 + 3 + 5).
CROSSREFS
KEYWORD
nonn
AUTHOR
Gary W. Adamson, Jul 31 2010
EXTENSIONS
Corrected by R. J. Mathar, Jul 21 2015
STATUS
approved