1,2

Conjectures: (1) k < 2n. (2) For every r, there exists a number S, nr < S < n(r+1) such that nS + 1 is prime.

Table of n, a(n) for n=1..72.

for n from 1 to 120 do k := n: while(not isprime(n*k+1)) do k := k+1:od:a[n] := k:od:seq(a[l], l=1..120); # Sascha Kurz

Cf. A034693.

Sequence in context: A161765 A232091 A164798 * A281072 A226951 A251557

Adjacent sequences: A087551 A087552 A087553 * A087555 A087556 A087557

nonn

Amarnath Murthy, Sep 13 2003

Edited by Ray Chandler and Don Reble, Sep 16 2003

approved