A278251 Least number with the prime signature of the n-th central polygonal number.

1, 1, 2, 2, 2, 6, 2, 2, 6, 2, 6, 6, 6, 2, 6, 2, 2, 30, 2, 8, 6, 2, 2, 12, 6, 2, 30, 6, 2, 6, 6, 12, 6, 6, 2, 6, 6, 6, 30, 2, 6, 6, 2, 6, 6, 6, 6, 30, 6, 6, 30, 2, 6, 6, 6, 2, 30, 6, 2, 30, 2, 6, 30, 2, 6, 30, 6, 2, 60, 12, 2, 6, 2, 6, 6, 30, 2, 6, 2, 2, 60, 2, 30, 6, 6, 6, 6, 6, 30, 30, 2, 2, 6, 6, 6, 30, 6, 6, 6, 6, 2, 210, 2, 30, 6, 6, 2, 30, 30, 6, 30, 2, 2

Offset: 0

Author

Antti Karttunen, Nov 21 2016

Keywords

• nonn

Comments

Almost all terms seem to be primorials, 4871 of the first 5212, in other words, most terms of A002061 (in the same range) are squarefree.

Links

• Antti Karttunen, Table of n, a(n) for n = 0..5211

Crossrefs

Cf. A002061, A046523.

Cf. also A278246, A278247, A278253.

Programs

Scheme

(define (A278251 n) (A046523 (A002061 n)))

Formula

a(n) = A046523(A002061(n)).