A356425 Sum of divisors of numbers of least prime signature: a(n) = A000203(A025487(n)).

1, 3, 7, 12, 15, 28, 31, 60, 72, 63, 91, 124, 168, 127, 195, 252, 360, 255, 403, 546, 508, 576, 600, 744, 511, 819, 1170, 1020, 1344, 1240, 1512, 1023, 1651, 2418, 2044, 2880, 2520, 2821, 3048, 2047, 3600, 3315, 4368, 3751, 4914, 4092, 5952, 5080, 6045, 6120

Offset: 1

Author

Hal M. Switkay, Dec 11 2022

Keywords

• nonn

Comments

This sequence is to A146288 as sigma (A000203, the sum of divisors function) is to tau (A000005, the number of divisors function).

Links

• Hal M. Switkay, Table of n, a(n) for n = 1..67

Crossrefs

Cf. A000005, A000203, A025487, A146288.

Programs

Mathematica

s = {1}; Do[If[GreaterEqual @@ (f = FactorInteger[n])[[;;,2]] && PrimePi[f[[-1,1]]] == Length[f], AppendTo[s, DivisorSigma[1,n]]], {n, 2, 2000}]; s (* Amiram Eldar, Dec 12 2022 *)