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

Author

Allan C. Wechsler, Oct 13 2017

Keywords

• nonn

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)

Crossrefs

Cf. A002110, A004394, A025487.

Programs

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 *)

Extensions

More terms from Michael De Vlieger, Oct 14 2017

More terms from Robert Price, Oct 19 2017