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

Offset: 3

Author

N. J. A. Sloane, Apr 01 2001

Keywords

• nonn

Crossrefs

Cf. A003418, A049711.

Programs

Mathematica

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

PARI

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

Formula

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