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 A278580 Numbers n such that Jacobi(n,23) = 1. 3
 1, 2, 3, 4, 6, 8, 9, 12, 13, 16, 18, 24, 25, 26, 27, 29, 31, 32, 35, 36, 39, 41, 47, 48, 49, 50, 52, 54, 55, 58, 59, 62, 64, 70, 71, 72, 73, 75, 77, 78, 81, 82, 85, 87, 93, 94, 95, 96, 98, 100, 101, 104, 105, 108, 110, 116, 117, 118, 119, 121, 123, 124, 127, 128, 131, 133, 139, 140, 141, 142, 144, 146 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Important for the study of Ramanujan numbers A000594. The first 11 terms, 1, 2, 3, 4, 6, 8, 9, 12, 13, 16, 18, are the quadratic residues mod 23 (see row 23 of A063987). LINKS Colin Barker, Table of n, a(n) for n = 1..1000 Index entries for linear recurrences with constant coefficients, signature (1,0,0,0,0,0,0,0,0,0,1,-1). FORMULA From Colin Barker, Nov 30 2016: (Start) a(n+11) = a(n) + 23. a(n) = a(n-1) + a(n-11) - a(n-12) for n>12. G.f.: x*(1 +x +x^2 +x^3 +2*x^4 +2*x^5 +x^6 +3*x^7 +x^8 +3*x^9 +2*x^10 +5*x^11) / ((1 -x)^2*(1 +x +x^2 +x^3 +x^4 +x^5 +x^6 +x^7 +x^8 +x^9 +x^10)) (End) PROG (PARI) Vec(x*(1+x+x^2+x^3+2*x^4+2*x^5+x^6+3*x^7+x^8+3*x^9+2*x^10+5*x^11) / ((1-x)^2*(1+x+x^2+x^3+x^4+x^5+x^6+x^7+x^8+x^9+x^10)) + O(x^100)) \\ Colin Barker, Nov 30 2016 CROSSREFS Cf. A010385, A000594, A063987, A278579. Sequence in context: A071403 A010407 A035240 * A028929 A308299 A274452 Adjacent sequences:  A278577 A278578 A278579 * A278581 A278582 A278583 KEYWORD nonn,easy AUTHOR N. J. A. Sloane, Nov 29 2016 STATUS approved

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Last modified May 25 19:44 EDT 2019. Contains 323576 sequences. (Running on oeis4.)