A083714 - OEIS

A083714

(greatest prime <= n) - (greatest prime factor of n).

0, 0, 0, 1, 0, 2, 0, 5, 4, 2, 0, 8, 0, 6, 8, 11, 0, 14, 0, 14, 12, 8, 0, 20, 18, 10, 20, 16, 0, 24, 0, 29, 20, 14, 24, 28, 0, 18, 24, 32, 0, 34, 0, 32, 38, 20, 0, 44, 40, 42, 30, 34, 0, 50, 42, 46, 34, 24, 0, 54, 0, 30, 54, 59, 48, 50, 0, 50, 44, 60, 0, 68, 0, 36, 68, 54, 62, 60, 0, 74

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OFFSET

1,6

COMMENTS

a(n) = A007917(n) - A006530(n);

n>1: a(n) = 0 iff n is prime.

LINKS

Table of n, a(n) for n=1..80.

MATHEMATICA

Join[{0}, Table[NextPrime[n+1, -1]-FactorInteger[n][[-1, 1]], {n, 2, 90}]] (* Harvey P. Dale, Nov 27 2011 *)

CROSSREFS

Cf. A083718, A083715, A083716, A083717.