A119728 Primes p such that p+1, p+2, p+3 and p+4 have equal number of divisors.

241, 13781, 19141, 21493, 50581, 61141, 76261, 77431, 94261, 95383, 95413, 98101, 104743, 104869, 134581, 141653, 142453, 152629, 153991, 158341, 160933, 165541, 169111, 199831, 201511, 203431, 206551, 229351, 233941, 235111, 253013, 273367

Offset

1,1

Links

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

Example

241 is a term since 242, 243, 244 and 245 all have 6 divisors:
{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}.

Mathematica

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

Crossrefs

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

Sequence in context: A007205 A008349 A094732 * A133327 A001361 A206842

Adjacent sequences: A119725 A119726 A119727 * A119729 A119730 A119731

Keyword

nonn

Author

Zak Seidov, Jul 29 2006

Status

approved