cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A062061 Numbers k such that prime(k)+1 divides k^2.

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%I A062061 #12 Apr 23 2022 13:16:58
%S A062061 2,4,70,516,174080,292050,637320,687105342,14342420320,214517880600
%N A062061 Numbers k such that prime(k)+1 divides k^2.
%C A062061 a(9) > 3*10^9. - _Donovan Johnson_, Oct 14 2009
%C A062061 a(11) > 3*10^11. - _Giovanni Resta_, Apr 15 2017
%e A062061 Prime(4)+1 = 7+1 divides 4^2, so 4 is a term of the sequence.
%t A062061 Select[Range[10^6], Mod[ #^2, Prime[ # ] + 1] == 0 &]
%t A062061 Select[Range[640000],PowerMod[#,2,Prime[#]+1]==0&] (* The program generates the first seven terms of the sequence. To generate more, increase the Range constant. *) (* _Harvey P. Dale_, Apr 23 2022 *)
%o A062061 (PARI) isok(n) = n^2 % (prime(n)+1) == 0; \\ _Michel Marcus_, Apr 15 2017
%Y A062061 Cf. A045924, A061437.
%K A062061 nonn
%O A062061 1,1
%A A062061 _Joseph L. Pe_, Feb 13 2002
%E A062061 a(8) from _Donovan Johnson_, Oct 14 2009
%E A062061 a(9)-a(10) from _Giovanni Resta_, Apr 15 2017