A243349 - OEIS

A243349

Difference between the n-th squarefree number and the index of its largest prime factor.

1, 1, 1, 2, 4, 3, 7, 6, 7, 10, 12, 10, 11, 17, 17, 14, 20, 19, 27, 20, 28, 27, 31, 25, 30, 33, 28, 38, 29, 37, 32, 44, 37, 50, 49, 48, 42, 43, 51, 59, 61, 48, 60, 66, 51, 52, 62, 72, 72, 57, 69, 60, 78, 72, 77, 65, 85, 82, 79, 87, 72, 75, 95, 76, 101, 90, 79, 80, 105

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OFFSET

1,4

COMMENTS

Different from A243289. A243348 gives the difference a(n) - A243289(n).

LINKS

Antti Karttunen, Table of n, a(n) for n = 1..10001

FORMULA

a(n) = A243291(A005117(n)).

a(n) = A005117(n) - A061395(A005117(n)).

MATHEMATICA

With[{s = Select[Range[120], SquareFreeQ]}, s - Table[PrimePi[FactorInteger[k][[-1, 1]]], {k, s}]] (* Amiram Eldar, Mar 04 2024 *)