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 A303217 A(n,k) is the n-th index of a Fibonacci number with exactly k distinct prime factors; square array A(n,k), n>=1, k>=1, read by antidiagonals. 19
 3, 8, 4, 15, 9, 5, 20, 16, 10, 6, 30, 24, 18, 12, 7, 40, 36, 27, 21, 14, 11, 70, 48, 42, 28, 33, 19, 13, 60, 81, 54, 44, 32, 35, 22, 17, 80, 72, 104, 56, 45, 52, 37, 25, 23, 90, 84, 110, 105, 64, 50, 55, 38, 26, 29, 140, 126, 88, 112, 136, 78, 57, 74, 39, 31, 43 (list; table; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Alois P. Heinz, Antidiagonals n = 1..18, flattened FORMULA A000045(A(n,k)) = A303218(n,k). A001221(A000045(A(n,k))) = k. EXAMPLE Square array A(n,k) begins:    3,  8, 15, 20, 30,  40,  70,  60,  80,  90, ...    4,  9, 16, 24, 36,  48,  81,  72,  84, 126, ...    5, 10, 18, 27, 42,  54, 104, 110,  88, 165, ...    6, 12, 21, 28, 44,  56, 105, 112,  96, 256, ...    7, 14, 33, 32, 45,  64, 136, 114, 100, 258, ...   11, 19, 35, 52, 50,  78, 148, 128, 108, 266, ...   13, 22, 37, 55, 57,  92, 152, 130, 132, 296, ...   17, 25, 38, 74, 63,  95, 164, 135, 138, 304, ...   23, 26, 39, 77, 66,  99, 182, 147, 156, 322, ...   29, 31, 46, 85, 68, 102, 186, 154, 184, 369, ... MAPLE F:= combinat[fibonacci]: with(numtheory): A:= proc() local h, p, q; p, q:= proc() [] end, 2;       proc(n, k)         while nops(p(k))

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Last modified May 31 22:29 EDT 2020. Contains 334756 sequences. (Running on oeis4.)