OFFSET
1,2
COMMENTS
FORMULA
O.g.f.: Sum_{n>0} 1/(1-A003319(n)*x^n).
EXAMPLE
a(4) = 15 because there are 13 connected permutations of {1,2,3,4} (these are counted by A003319) and 21/43 and 1/2/3/4.
MATHEMATICA
nn = 20; p = Sum[n! x^n, {n, 0, nn}]; i = 1 - 1/p; a = CoefficientList[Series[i, {x, 0, nn}], x]; s = Sum[1/(1 - a[[n + 1]] x^n), {n, 1, nn}]; Drop[ CoefficientList[Series[s, {x, 0, nn}], x], 1]
CROSSREFS
KEYWORD
nonn
AUTHOR
Geoffrey Critzer, Apr 29 2012
STATUS
approved