login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A187884 Numbers n such that n*p + 1 is not a square for any prime p. 2
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 (list; graph; refs; listen; history; text; internal format)
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: A191259 A184914 A232176 * A068977 A251538 A111284

Adjacent sequences:  A187881 A187882 A187883 * A187885 A187886 A187887

KEYWORD

nonn

AUTHOR

Michel Lagneau, Mar 15 2011

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified August 1 19:18 EDT 2021. Contains 346402 sequences. (Running on oeis4.)