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Search: id:A154772
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| A154772 |
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Numbers m such that 180 m^2 is the average of a twin prime pair. |
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+0
4
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| 1, 3, 7, 14, 22, 29, 41, 46, 62, 64, 67, 88, 167, 179, 207, 231, 239, 249, 263, 266, 286, 290, 309, 315, 322, 323, 326, 344, 350, 353, 354, 372, 392, 421, 444, 454, 458, 496, 505, 553, 560, 561, 571, 585, 613, 636, 647, 661, 669, 682, 745, 788, 790, 791, 815
(list; graph; listen)
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OFFSET
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1,2
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COMMENT
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Inspired by Z. Seidov's post to the SeqFan list, cf. link. This yields A154672 as 180 a(n)^2. Indeed, if N is such that N/5 is a square, then M=5m^2 and this can't by the average of a twin prime pair unless m=6a.
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LINKS
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Zak Seidov, "A154676", Jan 15 2009
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FORMULA
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a(n) = sqrt(A154672(n)/180)
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PROGRAM
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(PARI) for(i=1, 999, isprime(180*i^2+1) & isprime(180*i^2-1) & print1(i", "))
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CROSSREFS
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Cf. A037073, A154331, A154672.
Sequence in context: A001843 A033808 A161210 this_sequence A156859 A146931 A115285
Adjacent sequences: A154769 A154770 A154771 this_sequence A154773 A154774 A154775
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KEYWORD
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nonn
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AUTHOR
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M. F. Hasler (MHasler(AT)univ-ag.fr), Jan 15 2009
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