A328329 Lesser of twin primes p such that d(p+1) > d(q+1) for all lessers of twin primes q < p, where d(n) is the number of divisors of n (A000005).

3, 5, 11, 29, 59, 179, 239, 419, 1319, 2339, 3119, 3359, 6299, 7559, 21599, 21839, 33599, 35279, 42839, 55439, 100799, 110879, 287279, 415799, 957599, 1621619, 1713599, 1867319, 1940399, 2489759, 3991679, 6652799, 11531519, 18258239, 22822799, 26732159, 28828799

Offset: 1

Author

Amiram Eldar, Oct 12 2019

Keywords

• nonn

Comments

The corresponding values of d(p+1) are 3, 4, 6, 8, 12, 18, 20, 24, 32, 36, 40, 48, 54, 64, 72, 80, 84, 90, 96, 120, 126, 144, 160, 192, 216, 240, 252, 256, 270, 288, 320, 384, 432, 448, 480, 512, 576, ...

Crossrefs

Cf. A000005, A001359, A068507, A321995, A326392.

Programs

Mathematica

dm = DivisorSigma[0, 4]; s = {3}; Do[If[!PrimeQ[6n - 1] || !PrimeQ[6n + 1], Continue[]]; d = DivisorSigma[0, 6n]; If[d > dm, dm = d; AppendTo[s, 6n - 1]], {n, 1, 10^5}]; s