A104131 -id:A104131 - cp's OEIS frontend

A125137 a(n) = p^p + 1, where p = prime(n).

5, 28, 3126, 823544, 285311670612, 302875106592254, 827240261886336764178, 1978419655660313589123980, 20880467999847912034355032910568, 2567686153161211134561828214731016126483470, 17069174130723235958610643029059314756044734432, 10555134955777783414078330085995832946127396083370199442518

Offset: 1

N. J. A. Sloane, Jan 21 2007

nonn

Vincenzo Librandi, Table of n, a(n) for n = 1..77

See A125136 for factorizations. Cf. A088730, A125135.

Cf. A104131, A114846.

[p^p+1: p in PrimesUpTo(40)]; // Vincenzo Librandi, Mar 27 2014

Table[Prime[n]^Prime[n] + 1, {n , 20}] (* Vincenzo Librandi, Mar 27 2014 *)

a(n) = A051674(n)+1. - R. J. Mathar, Apr 23 2007

A104132 Largest prime factor of pip(n)^pip(n)-1 where pip(n) is the n-th prime-indexed prime.

Original entry on oeis.org

13, 71, 1806113, 2699538733, 568972471024107865287021434301977158534824481, 5926187589691497537793497756719

Offset: 1

Cino Hilliard, Mar 06 2005

Amiram Eldar, Table of n, a(n) for n = 1..10

Cf. A006450, A006530, A006486, A048861, A104131, A214812.

lpf[n_]:=Module[{p=Prime[Prime[n]]},FactorInteger[p^p-1][[-1,1]]]; Array[lpf,6] (* Harvey P. Dale, Nov 09 2017 *)

piptopipm1(n) = { local(x, y); for(x=1, n, y=pip(x)^pip(x)-1; print1(bdiv(y)", "); ) }
pip(n) = { return(prime(prime(n))) }
bdiv(n) = { local(x); x=ifactor(n); return(x[length(x)]) }
ifactor(n, m=0) = { local(f, j, k, flist); flist=[]; f=Vec(factor(n, m)); for(j=1, length(f[1]), for(k = 1, f[2][j], flist = concat(flist, f[1][j]) ); ); return(flist) }

a(n) = A006530(A048861(A006450(n))). - Amiram Eldar, May 23 2020

a(6) corrected by Harvey P. Dale, Nov 09 2017

cp's OEIS Frontend

A125137 a(n) = p^p + 1, where p = prime(n).

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