A278160 Least number with the prime signature of ((n+1)^2 - 1).

2, 8, 6, 24, 6, 48, 12, 48, 12, 120, 6, 120, 30, 96, 30, 288, 6, 360, 30, 120, 30, 240, 12, 240, 72, 120, 24, 840, 6, 960, 30, 192, 210, 360, 30, 360, 30, 240, 30, 1680, 6, 840, 60, 120, 60, 480, 12, 1440, 60, 360, 30, 1080, 30, 2160, 210, 240, 30, 840, 6, 840, 60, 384, 420, 1920, 30, 840, 30, 840, 30, 5040, 6, 720, 60, 120, 420, 840, 30, 3360, 48, 480, 48

Offset

1,1

Links

Antti Karttunen, Table of n, a(n) for n = 1..1024

Formula

a(n) = A046523(A005563(n)) = A046523(((n+1)^2)-1).

Mathematica

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

Prog

(Scheme)
(define (A278160 n) (A046523 (A005563 n)))
(define (A005563 n) (* n (+ 2 n)))

Crossrefs

Cf. A005563, A046523.

Cf. A001359 (positions of 6's).

Cf. also A278240, A278242, A278253, A278254, A278162.

Sequence in context: A373411 A100871 A111860 * A069895 A370925 A085590

Adjacent sequences: A278157 A278158 A278159 * A278161 A278162 A278163

Keyword

nonn

Author

Antti Karttunen, Nov 19 2016

Status

approved