A187884 Numbers n such that n*p + 1 is not a square for any prime p.

2, 6, 10, 14, 18, 20, 22, 23, 26, 28, 30, 34, 36, 37, 38, 42, 44, 46, 47, 50, 52, 53, 54, 58, 62, 66, 67, 68, 70, 74, 76, 78, 79, 82, 83, 86, 89, 90, 92, 94, 97, 98, 100, 102, 106, 108, 110, 113, 114, 116, 117, 118, 119, 121, 122, 124, 126, 127, 130, 131, 132, 134, 136

Offset

1,1

Links

Table of n, a(n) for n=1..63.

Maple

with(numtheory): for k from 1 to 200 do : q:=0:for n from 1 to 200 do : p:=ithprime(n):x:=sqrt(k*p+1) : if x=trunc(x) and q=0 then q:=1: else fi:od:if q=0 then printf(`%d, `, k):else
  fi:od:

Crossrefs

Cf. A187886.

Sequence in context: A184914 A232176 A366047 * A068977 A251538 A111284

Adjacent sequences: A187881 A187882 A187883 * A187885 A187886 A187887

Keyword

nonn

Author

Michel Lagneau, Mar 15 2011

Status

approved