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!)
A025026 Least non-residue mod n is 17. 0
1559, 2999, 3118, 5998, 6551, 8089, 8761, 13102, 13729, 14759, 16178, 16631, 17522, 18119, 19009, 21121, 21961, 23399, 24049, 27431, 27458, 27551, 28081, 29518, 31249, 33262, 33289, 33479, 35281, 35591, 36238, 36791, 38018, 42242, 43391, 43922, 43991 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..37.

PROG

(PARI) residue(n, m)=local(r); r=0; for(i=1, floor(m/2), if(i^2%m==n, r=1)); r

isA025026(n)={local(a); a=1; forprime(p=2, 13, a=a && residue(p, n)); a=a && !residue(17, n); a \\ Michael B. Porter, Apr 30 2010

(PARI) is(n)=issquare(Mod(2, n)) && issquare(Mod(3, n)) && issquare(Mod(5, n)) && issquare(Mod(7, n)) && issquare(Mod(11, n)) && issquare(Mod(13, n)) && !issquare(Mod(17, n)) \\ Charles R Greathouse IV, Jan 24 2020

CROSSREFS

Sequence in context: A252321 A252314 A186393 * A302057 A092001 A069475

Adjacent sequences:  A025023 A025024 A025025 * A025027 A025028 A025029

KEYWORD

nonn

AUTHOR

David W. Wilson

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 June 6 04:15 EDT 2020. Contains 334859 sequences. (Running on oeis4.)