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 A287920 Triangle T(n,k) read by rows: T(n,k) = floor(prime(n)/prime(k)), n >= k >= 1. 0
 1, 1, 1, 2, 1, 1, 3, 2, 1, 1, 5, 3, 2, 1, 1, 6, 4, 2, 1, 1, 1, 8, 5, 3, 2, 1, 1, 1, 9, 6, 3, 2, 1, 1, 1, 1, 11, 7, 4, 3, 2, 1, 1, 1, 1, 14, 9, 5, 4, 2, 2, 1, 1, 1, 1, 15, 10, 6, 4, 2, 2, 1, 1, 1, 1, 1, 18, 12, 7, 5, 3, 2, 2, 1, 1, 1, 1, 1, 20, 13, 8, 5, 3, 3, 2, 2, 1, 1, 1, 1, 1 (list; table; graph; refs; listen; history; text; internal format)
 OFFSET 1,4 COMMENTS Alternate name: triangle of quotients of prime(n)/prime(k), n >= k >= 1. LINKS EXAMPLE Triangle starts: n/k  1  2  3  4  5  6  7  8  9 10 11 12 1    1 2    1  1 3    2  1  1 4    3  2  1  1 5    5  3  2  1  1 6    6  4  2  1  1  1 7    8  5  3  2  1  1  1 8    9  6  3  2  1  1  1  1 9    11 7  4  3  2  1  1  1  1 10   14 9  5  4  2  2  1  1  1  1 11   15 10 6  4  2  2  1  1  1  1  1 12   18 12 7  5  3  2  2  1  1  1  1  1 T(11,3) = 6 because prime(11) = 31 and prime(3) = 5, and floor(31/5) = 6. PROG (PARI) T(n, k) = prime(n)\prime(k); tabl(nn) = for (n=1, nn, for (k=1, n, print1(T(n, k), ", ")); print()); \\ Michel Marcus, Jun 06 2017 CROSSREFS Cf. A000040 (primes), A130290 (1st column), A144769 (2nd column), A116572 (3rd column). Sequence in context: A112739 A225640 A194543 * A027293 A104762 A152462 Adjacent sequences:  A287917 A287918 A287919 * A287921 A287922 A287923 KEYWORD nonn,tabl AUTHOR Bob Selcoe, Jun 02 2017 STATUS approved

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Last modified June 25 07:53 EDT 2019. Contains 324347 sequences. (Running on oeis4.)