A120611 Sum of previous term and preceding divisors.

1, 2, 3, 4, 7, 8, 15, 19, 20, 27, 31, 32, 47, 48, 66, 72, 90, 111, 115, 116, 123, 127, 128, 175, 183, 187, 188, 242, 245, 253, 254, 384, 610, 613, 614, 617, 618, 624, 690, 826, 836, 862, 865, 866, 869, 870, 891, 922, 925, 926, 929, 930, 982, 985, 986, 989, 990

Offset

1,2

Links

Ivan Neretin, Table of n, a(n) for n = 1..10000

Formula

a(1) = 1, a(2) = 2, for n>=2, a(n+1) = a(n) + sum_{1<=k<n, a(k) divides a(n)} a(k).

Mathematica

a = {1, 2}; Do[AppendTo[a, Plus @@ Intersection[a, Divisors[a[[-1]]]]], {n, 3, 57}]; a (* Ivan Neretin, May 13 2015 *)

Crossrefs

Cf. A120610, A007497.

Sequence in context: A097110 A116961 A300486 * A092063 A227007 A370858

Adjacent sequences: A120608 A120609 A120610 * A120612 A120613 A120614

Keyword

nonn

Author

Franklin T. Adams-Watters, Jun 16 2006

Status

approved