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.

A078859 Least positive residues (mod 210) representing those residue classes which can be the lesser of twin prime pairs (A001359).

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%I A078859 #10 May 15 2017 23:05:43
%S A078859 3,5,11,17,29,41,59,71,101,107,137,149,167,179,191,197,209
%N A078859 Least positive residues (mod 210) representing those residue classes which can be the lesser of twin prime pairs (A001359).
%F A078859 Intersection[RRS(210), 2+RRS{210)]-2 and {3, 5}. RRS(210)=reduced residue system of 210=first 48=phi(210) terms of A008364; two additional term 3 and 5 are singular cases; 210k+r generates complete A001359 with suitable k and r taken from these 15+2 numbers.
%t A078859 With[{n = 4}, Function[P, Join[Select[Prime@ Range@ n, NextPrime@ # == # + 2 &], Select[Partition[Select[Range[P + 1], CoprimeQ[#, P] &], 2, 1], Differences@ # == {2} &][[All, 1]]]]@ Product[Prime@ i, {i, n}]] (* _Michael De Vlieger_, May 15 2017 *)
%Y A078859 Cf. A001359, A008364.
%K A078859 fini,full,nonn
%O A078859 1,1
%A A078859 _Labos Elemer_, Dec 13 2002