S001021


Smaller twin prime p such that phi(p-1) > phi(p+1), where phi is Euler’s totient function.

17, 29, 41, 59, 101, 107, 137, 149, 179, 191, 197, 227, 239, 269, 281, 311, 347, 419, 431, 461, 521, 569, 599, 617, 641, 659, 809, 821, 827, 857, 881, 1019, 1031, 1049, 1061, 1091, 1151, 1229, 1277, 1289, 1301, 1319, 1427, 1451, 1481, 1487, 1607, 1619, 1667

1

S001021

Garcia et al. call these primes unexceptional.

T. D. Noe, Plot of 1000 terms

T. D. Noe, Table of 1000 terms

Stephan Ramon Garcia, Elvis Kahoro, and Florian Luca, Primitive root discrepancy for twin primes, arXiv 1705.02485 (May 06 2017)

(Mma) t = {}; n = 0; While[Length[t] < 100, n++; p = Prime[n]; If[PrimeQ[p + 2] && EulerPhi[p - 1] > EulerPhi[p + 1], AppendTo[t, p]]]; t

Cf. S001022-S001025.

nonn

T. D. Noe, May 09 2017

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