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Search: id:A119711
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| A119711 |
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Primes p such that p+1, p+2 and p+3 have equal number of divisors. |
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+0
1
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| 229, 241, 373, 1831, 2053, 2503, 3109, 5861, 6053, 6151, 6871, 8293, 8821, 9161, 9829, 12049, 13591, 13781, 14293, 14887, 16087, 17737, 19141, 19333, 20389, 21493, 23333, 23509, 24151, 25771, 27109, 28807, 29269, 31337, 33413, 33941, 35509
(list; graph; listen)
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OFFSET
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1,1
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EXAMPLE
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229 is OK since 230, 231 and 232 all have 8 divisors:
{1,2,5,10,23,46,115,230}, {1,3,7,11,21,33,77,231} and {1,2,4,8,29,58,116,232}.
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MATHEMATICA
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Select[Prime@Range@5000, DivisorSigma[0, #+1]==DivisorSigma[0, #+2]==DivisorSigma[0, #+3]&]
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CROSSREFS
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Cf. A008329, A049234.
Sequence in context: A086002 A061783 A140017 this_sequence A062589 A094612 A112847
Adjacent sequences: A119708 A119709 A119710 this_sequence A119712 A119713 A119714
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KEYWORD
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nonn
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AUTHOR
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Zak Seidov (zakseidov(AT)yahoo.com), Jul 29 2006
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