1,2

A000079 is a subsequence; A002033(a(n)) = A074206(a(n)) = a(n)/2; A067824(a(n)) = a(n).

m=40, the proper divisors of 40 are 1, 2, 4, 5, 8, 10 and 20:

A067824(40) = 1+Sum(A067824(d): 1<=d<40) = 1+(1+2+4+2+8+6+16) = 40, therefore 40 is a term.

Sequence in context: A100685 A068799 A100778 this_sequence A100055 A104001 A048784

Adjacent sequences: A122405 A122406 A122407 this_sequence A122409 A122410 A122411

nonn

Reinhard Zumkeller (reinhard.zumkeller(AT)lhsystems.com), Sep 03 2006