A087548 Beginning with 1, smallest multiple of n such that a(n)*a(n-1) + 1 is a prime.

1, 2, 3, 4, 10, 6, 7, 16, 27, 10, 33, 12, 13, 42, 15, 16, 85, 18, 114, 20, 21, 22, 46, 72, 25, 52, 189, 84, 29, 60, 31, 192, 33, 34, 70, 36, 185, 228, 39, 80, 164, 420, 43, 220, 45, 138, 94, 48, 147, 50, 51, 312, 106, 270, 55, 168, 171, 348, 59, 60, 122, 620, 126, 256, 195

Offset

1,2

Links

Table of n, a(n) for n=1..65.

Maple

a[1] := 1:for n from 2 to 120 do l := 1:while(not isprime(a[n-1]*l*n+1)) do l := l+1: od:a[n] := l*n:od:seq(a[j], j=1..120); # Sascha Kurz

Crossrefs

Sequence in context: A356332 A065634 A364223 * A353959 A111619 A241083

Adjacent sequences: A087545 A087546 A087547 * A087549 A087550 A087551

Keyword

nonn

Author

Amarnath Murthy, Sep 13 2003

Extensions

Corrected and extended by Sascha Kurz, Sep 22 2003

Status

approved