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A088196
Largest number that is not a quadratic residue modulo prime(n).
9
2, 3, 6, 10, 11, 14, 18, 22, 27, 30, 35, 38, 42, 46, 51, 58, 59, 66, 70, 68, 78, 82, 86, 92, 99, 102, 106, 107, 110, 126, 130, 134, 138, 147, 150, 155, 162, 166, 171, 178, 179, 190, 188, 195, 198, 210, 222, 226, 227, 230, 238, 234, 250, 254, 262, 267, 270, 275, 278
OFFSET
2,1
COMMENTS
These are sometimes called quadratic non-residues modulo p(n). Denote a(n) by LQnR(p_n).
PROG
(PARI) qnrp(fr, n)= {/* The largest QnR modulo the primes */ local(m, p, fl, jj, j, v=[]); fr=max(fr, 2); for(i=fr, n, m=0; p=prime(i); jj=0; fl=2^p-1; j=2; while((j<=(p-1)/2), jj=(j^2)%p; fl-=2^jj; j++); j=p-1; while(m==0, if(bitand(2^j, fl), m=j); j--); v=concat(v, m)); print(v)}
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Ferenc Adorjan (fadorjan(AT)freemail.hu), Sep 23 2003
STATUS
approved