1,1

Equivalently, primes of the form 3n + 1.

Primes p dividing sum(k=0,p,C(2k,k)) -3 = A006134(p)-3 - Benoit Cloitre (benoit7848c(AT)orange.fr), Feb 08 2003

Primes p such that tau(p)==2 (mod 3) where tau(x) is the Ramanujan tau function (cf. A000594). - Benoit Cloitre (benoit7848c(AT)orange.fr), May 04 2003

Primes of the form x^2-xy+7y^2 with x and y nonnegative. - T. D. Noe (noe(AT)sspectra.com), May 07 2005

Primes p such that p^2 divides Sum[Sum[(2k)!/(k!)^2,{k,1,m}],{m,1,2(p-1)}]. - Alexander Adamchuk (alex(AT)kolmogorov.com), Jul 04 2006

A039701(A049084(a(n))) = A134323(A049084(a(n))) = 1. - Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Oct 21 2007

The set of primes of the form 3n + 1 is a superset of the set of greater of twin primes larger than five (A006512). - Paul Muljadi (paulmuljadi(AT)yahoo.com), Jun 05 2008

Also primes p such that the arithmetic mean of divisors of p^2 is an integer : sigma_1(p^2)/sigma_0(p^2) = C. (A000203(p^2)/A000005(p^2) = C) [From Ctibor O. Zizka (c.zizka(AT)email.cz), Sep 15 2008]

Is this the same sequence as A139492?

Primes p such that arithmetic mean of divisors of p^2 is an integer. [From Ctibor O. Zizka (c.zizka(AT)email.cz), Oct 20 2009]

N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).

M. Abramowitz and I. A. Stegun, eds., Handbook of Mathematical Functions, National Bureau of Standards Applied Math. Series 55, 1964 (and various reprintings), p. 870.

K. G. Reuschle, Tafeln Complexer Primzahlen. K\"{o}nigl. Akademie der Wissenschaften, Berlin, 1875, p. 1.

T. D. Noe, Table of n, a(n) for n=1..1000

M. Abramowitz and I. A. Stegun, eds., Handbook of Mathematical Functions, National Bureau of Standards, Applied Math. Series 55, Tenth Printing, 1972 [alternative scanned copy].

C. Banderier, Calcul de (-3/p)

A. Granville and G. Martin, Prime number races

a := [ ]: for n from 1 to 400 do if isprime(6*n+1) then a := [ op(a), n ]; fi; od: A002476 := n->a[n];

Select[6*Range[100] + 1, PrimeQ[ # ] &] - Stefan Steinerberger (stefan.steinerberger(AT)gmail.com), Apr 06 2006

(PARI) \primes of the form 3n+1 f(n) = for(x=1, n, y=3*x + 1; if(isprime(y), print1(y", "))) (from Cino Hilliard (hillcino368(AT)gmail.com), Feb 04 2004)

Cf. A045331.

For values of n see A024899. Primes of form 3n-1 give A003627.

These are the primes arising in A024892, A024899, A034936, A091178 gives prime index.

Cf. A006512.

Sequence in context: A038590 A129389 A107925 this_sequence A123365 A144921 A040079

Adjacent sequences: A002473 A002474 A002475 this_sequence A002477 A002478 A002479

nonn,nice,easy

N. J. A. Sloane (njas(AT)research.att.com).