

A119711


Primes p such that p+1, p+2 and p+3 have equal number of divisors.


5



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
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OFFSET

1,1


LINKS

Amiram Eldar, Table of n, a(n) for n = 1..10000


EXAMPLE

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}.


MATHEMATICA

Select[Prime@Range@5000, DivisorSigma[0, #+1]==DivisorSigma[0, #+2]==DivisorSigma[0, #+3]&]


CROSSREFS

Cf. A008329, A049234.
Sequence in context: A086002 A061783 A140017 * A062589 A250235 A250236
Adjacent sequences: A119708 A119709 A119710 * A119712 A119713 A119714


KEYWORD

nonn


AUTHOR

Zak Seidov, Jul 29 2006


STATUS

approved



