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 A091381 First differences of A091380. 5
 0, 2, 1, 5, 2, 3, 3, 1, 9, 1, 7, 3, 3, 1, 9, 6, 2, 6, -1, 4, 8, 5, 5, 6, 7, 1, 5, 2, 3, 14, 5, 5, 3, 10, 1, 7, 6, 1, 9, 6, 2, 5, 4, 7, 1, 13, 11, 5, 2, 3, 2, 2, 15, 5, 4, 9, 1, 7, 3, 3, 10, 14, -5, 8, 7, 14, 3, 13, 2, 3, 2, 12, 7, 6, 1, 9, 8, 3, 4, 15, 2, 5, 4, 8, 5, 5, 6, 7, 1, 5, 1, 18, 5, 8, 1, 9, 11, 3, 18 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Seemingly, the difference sequence is mostly positive. There are special characteristic features, where it is nonpositive (see A091383-A091385). LINKS Ferenc Adorjan, The sequence of largest quadratic residues modulo the primes PROG (PARI) {/* Difference sequence of the largest "mixed" QR modulo the primes */ d_lqxr(to)=local(v=[], k, r, q, p, e=1); for(i=2, to, p=prime(i); k=p-1; r=p%4-2; while(kronecker(k, p)<>r, k-=1); v=concat(v, k-e); e=k); print(v) } CROSSREFS Cf. A091380, A091382, A091383, A091384, A091385, A088191, A088197. Sequence in context: A090003 A136645 A247498 * A127156 A205106 A144019 Adjacent sequences:  A091378 A091379 A091380 * A091382 A091383 A091384 KEYWORD easy,sign AUTHOR Ferenc Adorjan (fadorjan(AT)freemail.hu) STATUS approved

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Last modified September 20 10:51 EDT 2021. Contains 347584 sequences. (Running on oeis4.)