A353301 Numbers k such that A004394(k)+1 is prime.

1, 2, 3, 4, 5, 7, 9, 11, 12, 18, 21, 24, 25, 28, 35, 45, 46, 50, 56, 70, 73, 76, 78, 79, 82, 89, 94, 105, 113, 116, 118, 121, 123, 124, 138, 139, 153, 157, 159, 164, 197, 201, 203, 210, 217, 253, 261, 273, 280, 283, 287, 342, 352, 356, 381, 396, 437, 450, 471

Offset

1,2

Comments

First differs from A306587 at n=11.

Links

Amiram Eldar, Table of n, a(n) for n = 1..300

Example

1 is a term since A004394(1)+1 = 1+1 = 2 is prime.

Mathematica

s = {}; abm = 0; k = 0; Do[ab = DivisorSigma[-1, n]; If[ab > abm, abm = ab; k++; If[PrimeQ[n + 1], AppendTo[s, k]]], {n, 1, 10^6}]; s

Crossrefs

Cf. A004394, A072828, A306587, A353300, A353302.

Sequence in context: A184112 A064005 A306587 * A339968 A316268 A026285

Adjacent sequences: A353298 A353299 A353300 * A353302 A353303 A353304

Keyword

nonn

Author

Amiram Eldar, Apr 10 2022

Status

approved