This site is supported by donations to The OEIS Foundation.

 Please make a donation to keep the OEIS running. We are now in our 55th year. In the past year we added 12000 new sequences and reached 8000 citations (which often say "discovered thanks to the OEIS"). We need to raise money to hire someone to manage submissions, which would reduce the load on our editors and speed up editing. Other ways to donate

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A119730 Primes p such that p+1, p+2, p+3, p+4 and p+5 have equal number of divisors. 0
 13781, 19141, 21493, 50581, 142453, 152629, 253013, 298693, 307253, 346501, 507781, 543061, 845381, 1079093, 1273781, 1354501, 1386901, 1492069, 1546261, 1661333, 1665061, 1841141, 2192933, 2208517, 2436341, 2453141, 2545013 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS EXAMPLE 13781 is OK since 13782, 13783, 13784, 13785 and 13786 all have 8 divisors: {1,2,3,6,2297,4594,6891,13782}, {1,7,11,77,179,1253,1969,13783}, {1,2,4,8,1723,3446,6892,13784}, {1,3,5,15,919,2757,4595,13785} and {1,2,61,113,122,226,6893,13786}. MATHEMATICA Select[Prime@Range[1000000], DivisorSigma[0, #+1]==DivisorSigma[0, #+2]==DivisorSigma[0, #+3]==DivisorSigma[0, #+4]==DivisorSigma[0, #+5]&] endQ[n_]:= Length[Union[DivisorSigma[0, (n + Range[5])]]]==1; Select[Prime[ Range[ 200000]], endQ] (* Harvey P. Dale, Jan 16 2019 *) CROSSREFS Cf. A008329, A049234. Sequence in context: A235184 A270639 A031807 * A204839 A208487 A188102 Adjacent sequences:  A119727 A119728 A119729 * A119731 A119732 A119733 KEYWORD nonn AUTHOR Zak Seidov, Jul 29 2006 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified December 6 04:14 EST 2019. Contains 329784 sequences. (Running on oeis4.)