A354945 - OEIS

A354945

a(n) is the least k > 0 such that n is a non-isolated divisor of k!.

2, 2, 3, 4, 5, 5, 7, 6, 6, 6, 11, 11, 13, 7, 6, 6, 17, 17, 19, 7, 7, 11, 23, 10, 10, 13, 9, 9, 29, 29, 31, 11, 11, 17, 7, 7, 37, 19, 13, 13, 41, 41, 43, 11, 11, 23, 47, 14, 14, 14, 17, 17, 53, 11, 11, 11, 19, 29, 59, 59, 61, 31, 8, 8, 13, 13, 67, 23, 23, 23

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OFFSET

1,1

COMMENTS

A positive divisor d of m is non-isolated if either d-1 or d+1 also divides m.

For any v > 1, v appears A133951(v)-A133951(v-1) times.

LINKS

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

FORMULA

A002034(n) <= a(n) <= n for any n > 1.

a(p) = p for any prime number p.

a(n) = max(A002034(n), min(A002034(n-1), A002034(n+1))) for any n > 1.