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Primes p such that p+1, p+2, p+3 and p+4 have equal number of divisors.
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%I #13 May 25 2020 18:45:36

%S 241,13781,19141,21493,50581,61141,76261,77431,94261,95383,95413,

%T 98101,104743,104869,134581,141653,142453,152629,153991,158341,160933,

%U 165541,169111,199831,201511,203431,206551,229351,233941,235111,253013,273367

%N Primes p such that p+1, p+2, p+3 and p+4 have equal number of divisors.

%H Amiram Eldar, <a href="/A119728/b119728.txt">Table of n, a(n) for n = 1..10000</a>

%e 241 is a term since 242, 243, 244 and 245 all have 6 divisors:

%e {1,2,11,22,121,242},{1,3,9,27,81,243},{1,2,4,61,122,244} and {1,5,7,35,49,245}.

%t Select[Prime@Range@50000,DivisorSigma[0,#+1]==DivisorSigma[0,#+2]==DivisorSigma[0,#+3]==DivisorSigma[0,#+4]&]

%Y Cf. A008329, A049234, A119705, A119711, A119730, A119740.

%K nonn

%O 1,1

%A _Zak Seidov_, Jul 29 2006