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A129597
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Central diagonal of array A129595.
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5
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1, 4, 6, 16, 10, 24, 14, 64, 54, 40, 22, 96, 26, 56, 90, 256, 34, 216, 38, 160, 126, 88, 46, 384, 250, 104, 486, 224, 58, 360, 62, 1024, 198, 136, 350, 864, 74, 152, 234, 640, 82, 504, 86, 352, 810, 184, 94, 1536, 686, 1000, 306, 416, 106, 1944, 550, 896, 342
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OFFSET
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1,2
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COMMENTS
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These are the positions of first appearances of each positive integer in A346704. - Gus Wiseman, Oct 16 2021
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LINKS
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FORMULA
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If g = A006530(n) is the greatest prime factor of n > 1, then a(n) = 2n^2/g.
(End)
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MATHEMATICA
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Table[If[n==1, 1, 2*n^2/FactorInteger[n][[-1, 1]]], {n, 100}] (* Gus Wiseman, Aug 10 2021 *)
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PROG
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CROSSREFS
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The sum of prime indices of a(n) is 2*A056239(n) - A061395(n) + 1 for n > 1.
The version for odd indices is A342768(n) = a(n)/2 for n > 1.
Except the first term, the sorted version is 2*A346635.
These are the positions of first appearances in A346704.
A001221 counts distinct prime factors.
A001222 counts prime factors with multiplicity.
A346633 adds up the even bisection of standard compositions (odd: A209281).
A346698 adds up the even bisection of prime indices (reverse: A346699).
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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