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 A119711 Primes p such that p+1, p+2 and p+3 have equal number of divisors. 0

%I

%S 229,241,373,1831,2053,2503,3109,5861,6053,6151,6871,8293,8821,9161,

%T 9829,12049,13591,13781,14293,14887,16087,17737,19141,19333,20389,

%U 21493,23333,23509,24151,25771,27109,28807,29269,31337,33413,33941,35509

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

%e 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}.

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

%Y Cf. A008329, A049234.

%K nonn

%O 1,1

%A _Zak Seidov_, Jul 29 2006

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Last modified December 14 09:49 EST 2018. Contains 318095 sequences. (Running on oeis4.)