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A056738
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Positions where 2's occur in A056731.
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3
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1, 4, 8, 13, 20, 28, 37, 47, 59, 72, 86, 101, 117, 135, 154, 174, 195, 217, 240, 264, 290, 317, 345, 374, 404, 435, 467, 500, 535, 571, 608, 646, 685, 725, 766, 808, 851, 896, 942, 989, 1037, 1086, 1136, 1187, 1239, 1292, 1346, 1402, 1459, 1517, 1576, 1636
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OFFSET
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1,2
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LINKS
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FORMULA
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a(n+1) = a(n) + (n+1) + the number of a(k)'s <= n, 1 <= k <= n and a(1) = 1.
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EXAMPLE
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a(9) = a(8) + 8 + the number of a(k)'s <= 8 = 47 + 8 + 1 + 3 ( a(3) is <= 8) = 59.
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MATHEMATICA
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f[1] = 1; f[n_] := f[n] = Block[ {k = 1}, While[ f[k] < n, k++ ]; Return[ f[n - 1] + n + k ]]; Table[ f[n], {n, 0, 60} ]
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CROSSREFS
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KEYWORD
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nonn,easy
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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