A278228 Least number with the prime signature of prime(n)+1.

2, 4, 6, 8, 12, 6, 12, 12, 24, 30, 32, 6, 30, 12, 48, 24, 60, 6, 12, 72, 6, 48, 60, 60, 12, 30, 24, 72, 30, 30, 128, 60, 30, 60, 60, 24, 6, 12, 120, 30, 180, 30, 192, 6, 60, 72, 12, 96, 60, 30, 60, 240, 12, 180, 30, 120, 120, 48, 6, 30, 12, 60, 60, 120, 6, 30, 12, 12, 60, 60, 30, 360, 48, 30, 60, 384, 210, 6, 30, 30, 420, 6, 432, 30, 120, 60, 180, 6, 210, 48

Offset

1,1

Links

Antti Karttunen, Table of n, a(n) for n = 1..10000

Formula

a(n) = A046523(A000040(n)+1).

Mathematica

Table[Times @@ MapIndexed[(Prime@ First@ #2)^#1 &, #] &@ If[Length@ # == 1 && #[[1, 1]] == 1, {0}, Reverse@ Sort@ #[[All, -1]]] &@ FactorInteger[ Prime@ n + 1], {n, 120}] (* Michael De Vlieger, Nov 21 2016 *)

Prog

(Scheme) (define (A278228 n) (A046523 (+ 1 (A000040 n))))

Crossrefs

Cf. A000040, A046523.

Cf. A174801 (positions of terms <= 6).

Cf. also A278227, A278229, A278230.

Sequence in context: A345113 A099994 A068065 * A028328 A360408 A274262

Adjacent sequences: A278225 A278226 A278227 * A278229 A278230 A278231

Keyword

nonn

Author

Antti Karttunen, Nov 19 2016

Status

approved