A293635 Positions of superabundant numbers in the sequence of primorial products.

1, 2, 3, 4, 6, 8, 11, 12, 13, 17, 20, 24, 27, 34, 36, 43, 47, 55, 67, 84, 95, 107, 112, 138, 166, 183, 211, 220, 252, 261, 264, 314, 348, 390, 406, 457, 476, 500, 582, 652, 726, 756, 839, 870, 907, 1046, 1188, 1199, 1294, 1310, 1359, 1500, 1553, 1615, 1835

Offset

1,2

Comments

Indices of A004394 in A025487; the latter is easily seen to contain the former.

Links

Michael De Vlieger, Table of n, a(n) for n = 1..300 (first 84 terms from Robert Price)

Mathematica

Block[{P = Product[Prime@ i, {i, 7}], s, t, u}, s = Array[DivisorSigma[1, #]/# &, P]; t = Array[If[# == 1, {0}, Sort[FactorInteger[#][[All, -1]], Greater]] &, P]; u = Values[PositionIndex@ t][[All, 1]]; Map[FirstPosition[u, #][[1]] &, FirstPosition[s, #][[1]] & /@ Union@ FoldList[Max, s]]] (* Michael De Vlieger, Oct 14 2017 *)

Crossrefs

Cf. A002110, A004394, A025487.

Sequence in context: A189704 A223543 A306802 * A123586 A257121 A039500

Adjacent sequences: A293632 A293633 A293634 * A293636 A293637 A293638

Keyword

nonn

Author

Allan C. Wechsler, Oct 13 2017

Extensions

More terms from Michael De Vlieger, Oct 14 2017

More terms from Robert Price, Oct 19 2017

Status

approved