OFFSET
1,2
LINKS
Alois P. Heinz, Table of n, a(n) for n = 1..10000
EXAMPLE
a(8) = 10; all nonempty subsets S of {1, 2, ..., 8} with pairwise coprime elements that are maximal with respect to inclusion of elements < max(S) are: {1}, {1,2}, {1,2,3}, {1,3,4}, {1,5,6}, {1,2,3,5}, {1,3,4,5}, {1,2,3,5,7}, {1,3,4,5,7}, {1,3,5,7,8}.
MAPLE
with(numtheory):
b:= n-> mul(ilog[j](n), j={ithprime(i)$i=1..pi(n)} minus factorset(n)):
a:= proc(n) option remember; b(n) +`if`(n<2, 0, a(n-1)) end:
seq(a(n), n=1..80);
MATHEMATICA
b[n_] := Product[Log[p, n] // Floor, {p, Select[Range[n-1], PrimeQ[#] && GCD[n, #] == 1&]}];
A187092 = Array[b, 100] // Accumulate (* Jean-François Alcover, Mar 27 2017, adapted from Maple *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Alois P. Heinz, Mar 04 2011
STATUS
approved