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A323136

a(n) is the least power of a prime that n reaches under the map x -> A070229(x), or -1 if we never reach a power of a prime.

1, 2, 3, 4, 5, 9, 7, 8, 9, 25, 11, 25, 13, 49, 25, 16, 17, 49, 19, 25, 49, 121, 23, 27, 25, 169, 27, 49, 29, 49, 31, 32, 121, 289, 49, 169, 37, 361, 169, 121, 41, 49, 43, 121, 121, 529, 47, 289, 49, 121, 289, 169, 53, 361, 121, 121, 361, 841, 59, 169, 61, 961

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OFFSET

1,2

COMMENTS

The powers of primes correspond to A000961.

Apparently, a(n) > 0 for all n > 0.

LINKS

Rémy Sigrist, Table of n, a(n) for n = 1..10000

FORMULA

a(n) = n iff n belongs to A000961.

A006530(a(n)) >= A006530(n) when a(n) > 0.

EXAMPLE