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A078859 Least positive residues (mod 210) representing those residue classes which can be the lesser of twin prime pairs (A001359). 9
3, 5, 11, 17, 29, 41, 59, 71, 101, 107, 137, 149, 167, 179, 191, 197, 209 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..17.

FORMULA

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.

MATHEMATICA

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 *)

CROSSREFS

Cf. A001359, A008364.

Sequence in context: A069233 A329946 A063700 * A054799 A093326 A001359

Adjacent sequences:  A078856 A078857 A078858 * A078860 A078861 A078862

KEYWORD

fini,full,nonn

AUTHOR

Labos Elemer, Dec 13 2002

STATUS

approved

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Last modified April 18 02:18 EDT 2021. Contains 343072 sequences. (Running on oeis4.)