A328329 - OEIS

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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

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OFFSET

1,1

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, ...

LINKS

Table of n, a(n) for n=1..37.

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

CROSSREFS

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

Sequence in context: A292539 A046134 A177932 * A326392 A213210 A279674

Adjacent sequences: A328326 A328327 A328328 * A328330 A328331 A328332

KEYWORD

nonn

AUTHOR

Amiram Eldar, Oct 12 2019

STATUS

approved