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 A300288 Irregular triangle read by rows: row n contains numbers k such that -n<=k<=n and gcd(k, 2*n+1) != 1. 1
 0, 0, 0, -3, 0, 3, 0, 0, -6, -5, -3, 0, 3, 5, 6, 0, 0, -9, -7, -6, -3, 0, 3, 6, 7, 9, 0, -10, -5, 0, 5, 10, -12, -9, -6, -3, 0, 3, 6, 9, 12, 0, 0, -15, -12, -11, -9, -6, -3, 0, 3, 6, 9, 11, 12, 15, -15, -14, -10, -7, -5, 0, 5, 7, 10, 14, 15, 0, -18, -15, -13, -12, -9, -6, -3, 0, 3, 6, 9, 12, 13, 15, 18, 0 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,4 COMMENTS Row n contains 2*n+1 - phi(2*n+1) = A053193(n) terms. Row n has just one term (namely 0) if 2*n+1 is prime. LINKS FORMULA T(n,k) = A299714(n,k) - n. EXAMPLE Triangle starts: [01]: 0, [02]: 0, [03]: 0, [04]: -3, 0, 3, [05]: 0, [06]: 0, [07]: -6, -5, -3, 0, 3, 5, 6, [08]: 0, [09]: 0, [10]: -9, -7, -6, -3, 0, 3, 6, 7, 9, [11]: 0, [12]: -10, -5, 0, 5, 10, [13]: -12, -9, -6, -3, 0, 3, 6, 9, 12, [14]: 0, [15]: 0, [16]: -15, -12, -11, -9, -6, -3, 0, 3, 6, 9, 11, 12, 15, [17]: -15, -14, -10, -7, -5, 0, 5, 7, 10, 14, 15, [18]: 0, [19]: -18, -15, -13, -12, -9, -6, -3, 0, 3, 6, 9, 12, 13, 15, 18, [20]: 0, ... PROG (PARI) is(n, k)= ( gcd(k, 2*n+1)!=1 ); for (n=1, 33, for (k=-n, +n, if (is(n, k), print1(k, ", ") ); ); ); CROSSREFS Cf. A299714. Sequence in context: A247704 A127802 A165951 * A340555 A094901 A030220 Adjacent sequences: A300285 A300286 A300287 * A300289 A300290 A300291 KEYWORD sign,tabf AUTHOR Joerg Arndt, Mar 02 2018 STATUS approved

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Last modified February 4 19:22 EST 2023. Contains 360059 sequences. (Running on oeis4.)