A060360 - OEIS

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A060360

a(n) = k - (largest prime < k), where k = lcm(1..n).

1, 1, 1, 1, 1, 1, 17, 17, 19, 19, 23, 23, 23, 17, 43, 43, 1, 1, 1, 1, 1, 1, 29, 29, 41, 41, 1, 1, 43, 1, 1, 1, 1, 1, 43, 43, 43, 43, 47, 47, 83, 83, 83, 83, 1, 1, 83, 83, 83, 83, 61, 61, 61, 61, 61, 61, 149, 149, 1, 1, 1, 97, 97, 97, 89, 89, 89, 89, 109, 109

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OFFSET

3,7

LINKS

Table of n, a(n) for n=3..72.

FORMULA

a(n) = A049711(A003418(n)). - Michel Marcus, Mar 20 2018

MATHEMATICA

lcmp[n_]:=Module[{c=LCM@@Range[n]}, c-NextPrime[c, -1]]; Array[lcmp, 80, 3] (* Harvey P. Dale, Dec 22 2012 *)

PROG

(PARI) a(n) = my(lc = lcm([1..n])); lc - precprime(lc-1); \\ Michel Marcus, Mar 20 2018

CROSSREFS