A119288 - OEIS

A119288

a(n) is the second smallest prime factor of n, or 1 if n is a prime power.

1, 1, 1, 1, 1, 3, 1, 1, 1, 5, 1, 3, 1, 7, 5, 1, 1, 3, 1, 5, 7, 11, 1, 3, 1, 13, 1, 7, 1, 3, 1, 1, 11, 17, 7, 3, 1, 19, 13, 5, 1, 3, 1, 11, 5, 23, 1, 3, 1, 5, 17, 13, 1, 3, 11, 7, 19, 29, 1, 3, 1, 31, 7, 1, 13, 3, 1, 17, 23, 5, 1, 3, 1, 37, 5, 19, 11, 3, 1, 5, 1, 41, 1, 3, 17, 43, 29, 11, 1, 3, 13, 23

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OFFSET

1,6

COMMENTS

Least prime factor of {n divided by the maximal power of the least prime factor of n}. - after the original name of the sequence.

a(n) = A020639(A028234(n)).

a(n) = 1 iff n is a prime power: a(A000961(n))=1 and a(A024619(n))>1.

LINKS

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

FORMULA

A010055(n) = 0^(a(n)-1). - Reinhard Zumkeller, May 13 2006

MATHEMATICA