A378201 a(n) = 2*n mod q, where q is the greatest prime such that 2*n - q is also prime.
0, 0, 3, 3, 5, 3, 3, 5, 3, 3, 5, 3, 5, 7, 3, 3, 5, 7, 3, 5, 3, 3, 5, 3, 5, 7, 3, 5, 7, 3, 3, 5, 7, 3, 5, 3, 3, 5, 7, 3, 5, 3, 5, 7, 3, 5, 7, 19, 3, 5, 3, 3, 5, 3, 3, 5, 3, 5, 7, 13, 11, 13, 19, 3, 5, 3, 5, 7, 3, 3, 5, 7, 11, 11, 3, 3, 5, 7, 3, 5, 7, 3, 5, 3, 5, 7, 3, 5, 7, 3, 3, 5, 7, 11, 11, 3, 3, 5
Offset: 2
Keywords
Crossrefs
Cf. A002373.
Programs
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Mathematica
Table[Module[{p = 2, q}, While[True, q = 2 n - p; If[PrimeQ[p] && PrimeQ[q], Break[]]; p = NextPrime[p]]; Mod[2 n, q]], {n, 2, 100}]