cp's OEIS Frontend

A091385 Distance (A091382) of primes from the largest quadratic "mixed" residues modulo the primes (A091380), where the latter is non-monotonic.

%I A091385 #5 Mar 14 2018 03:51:31
%S A091385 2,7,11,7,11,11,7,17,7,7,7,13,11,13,7,11,7,11,13,7,11,13,11,7,11,11,
%T A091385 13,7,7,11,13,19,11,17,11,7,7,7,13,13,17,11,11,17,11,13,19,11,13,11,7,
%U A091385 7,11,19,11,11,7,13,11,11,13,13,7,13,17,13,11,17,11,19,11,11,11,13,23,7,17,7
%N A091385 Distance (A091382) of primes from the largest quadratic "mixed" residues modulo the primes (A091380), where the latter is non-monotonic.
%C A091385 For n > 1, the values are some odd primes, but never < 7. The maximum value increases very slowly, it only reaches 43 for the first 10^5 primes.
%H A091385 Ferenc Adorjan, <a href="http://web.axelero.hu/fadorjan/qrp.pdf">The sequence of largest quadratic residues modulo the primes</a>
%o A091385 (PARI) {/* The distance of LQxR from the primes where the sequence of the largest "mixed" QR modulo the primes is non-monotonic */ lqxr_nm_pd(to)=local(v=[],k,r,q,p,e=1,n=0,i=1); while(n<to,i+=1;p=prime(i);k=p-1;r=p%4-2; while(kronecker(k,p)<>r,k-=1); if(k-e<=0,v=concat(v,p-k);n+=1);e=k); print(i);print(v) }
%Y A091385 Cf. A091380, A091381, A091382, A091383, A091384, A088195, A088201.
%K A091385 easy,nonn
%O A091385 1,1
%A A091385 Ferenc Adorjan (fadorjan(AT)freemail.hu)