The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History for A320077 (Bold, blue-underlined text is an addition; faded, red-underlined text is a ~~deletion~~.)
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A320077

a(n) is smallest positive integer i such that sum of numerator and denominator of sum of j^(-i), when j=1..n, is prime.
(history; published version)

#24 by N. J. A. Sloane at Tue Nov 20 05:26:54 EST 2018

STATUS

proposed

approved

#23 by Chai Wah Wu at Tue Nov 20 00:00:26 EST 2018

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editing

proposed

#22 by Chai Wah Wu at Mon Nov 19 23:17:32 EST 2018

COMMENTS

a(18) = a(25) = a(31) = 6, a(19) = a(22) = a(37) = 5, a(20) = a(27) = a(35) = a(36) = a(39) = a(48) = 1, a(23) = a(38) = a(49) = 2, a(24) = a(29) = a(42) = 3, a(26) = 12, a(28) = 75, a(30) = 8, a(33) = 7, a(41) = 121, a(44) = 1052, a(46) = 125, a(47) = 1527. - Chai Wah Wu, Nov 19 2018

STATUS

approved

editing

#21 by Susanna Cuyler at Mon Nov 19 19:37:25 EST 2018

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proposed

approved

#20 by Chai Wah Wu at Mon Nov 19 15:28:46 EST 2018

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editing

proposed

#19 by Chai Wah Wu at Mon Nov 19 15:28:00 EST 2018

COMMENTS

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approved

editing

#18 by Giovanni Resta at Wed Nov 14 04:38:59 EST 2018

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reviewed

approved

#17 by Vaclav Kotesovec at Wed Nov 14 03:25:18 EST 2018

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proposed

reviewed

#16 by Vaclav Kotesovec at Wed Nov 14 03:21:02 EST 2018

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editing

proposed

#15 by Vaclav Kotesovec at Wed Nov 14 03:16:58 EST 2018

MATHEMATICA

a[n_] := Do[s = HarmonicNumber[n, r]; If[PrimeQ[Numerator[s] + Denominator[s]], Return[r]], {r, 1, Infinity}]; Table[a[n], {n, 1, 16}] (* Vaclav Kotesovec, Nov 14 2018 *)

STATUS

proposed

editing