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A342728
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a(n) is the least number k such that A066323(k) = n.
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6
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0, 1, 2, 3, 4, 5, 6, 7, 23, 39, 55, 71, 87, 103, 359, 615, 871, 1127, 1383, 1639, 5735, 9831, 13927, 18023, 22119, 26215, 91751, 157287, 222823, 288359, 353895, 419431, 1468007, 2516583, 3565159, 4613735, 5662311, 6710887, 23488103, 40265319, 57042535, 73819751
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OFFSET
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0,3
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COMMENTS
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a(n) is the least number k whose sum of digits in base i-1 (or in base -4) is n.
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LINKS
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FORMULA
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a(n) = n for n <= 7, and a(n) = a(n-1) + 16*a(n-6) - 16*a(n-7) for n > 7.
G.f.: x*(1 + x + x^2 + x^3 + x^4 + x^5 - 15*x^6)/(1 - x - 16*x^6 + 16*x^7). - Stefano Spezia, Mar 20 2021
a(3*n+1) = (24 + (4^n)*(25 - 9*(-1)^n))/40.
a(3*n+2) = (24 + (4^n)*(50 + 6*(-1)^n))/40.
a(3*n+3) = (24 + (4^n)*(75 + 21*(-1)^n))/40. (End)
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MATHEMATICA
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Join[{0}, LinearRecurrence[{1, 0, 0, 0, 0, 16, -16}, Range[7], 50]]
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CROSSREFS
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KEYWORD
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nonn,base,easy
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AUTHOR
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STATUS
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approved
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