A143174 - OEIS

A143174

a(1)=1. a(n) = smallest positive multiple of n such that |a(n)-a(n-1)| is prime.

1, 4, 6, 4, 15, 12, 7, 24, 27, 10, 33, 36, 13, 42, 45, 16, 119, 18, 209, 60, 63, 22, 69, 72, 25, 78, 81, 28, 87, 90, 31, 128, 99, 68, 70, 72, 74, 76, 39, 80, 82, 84, 43, 132, 135, 46, 329, 48, 245, 250, 51, 104, 106, 108, 55, 168, 171, 58, 767, 120, 61, 372

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OFFSET

1,2

COMMENTS

a(n+1) - a(n) = A143175(n), which is prime.

a(62)=372. a(63) does not exist because 3 divides k*63-372 for all positive integers k - Owen Whitby, Sep 25 2008

LINKS

Table of n, a(n) for n=1..62.

MATHEMATICA

spm[{n_, a_}]:=Module[{k=1}, While[!PrimeQ[k(n+1)-a], k++]; {n+1, k(n+1)}]; NestList[spm, {1, 1}, 61][[All, 2]] (* Harvey P. Dale, Nov 26 2020 *)

CROSSREFS

Cf. A143175.