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A285792
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Primes equal to an octagonal number plus 1.
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5
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2, 41, 97, 281, 409, 937, 1409, 2297, 4721, 5209, 6257, 8009, 8641, 12161, 14561, 18097, 21001, 23057, 24121, 26321, 27457, 37409, 42961, 50441, 52009, 55217, 56857, 60209, 70841, 76481, 90481, 139537, 147409, 152777, 161009, 169457, 172321, 227977, 238009
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OFFSET
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1,1
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COMMENTS
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LINKS
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MATHEMATICA
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Select[PolygonalNumber[8, Range[300]]+1, PrimeQ] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Oct 22 2017 *)
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PROG
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(PARI) pg(m, n) = (n^2*(m-2)-n*(m-4))/2 \\ n-th m-gonal number
maxk=300; L=List(); for(k=1, maxk, if(isprime(p=pg(8, k) + 1), listput(L, p))); Vec(L)
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CROSSREFS
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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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