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Triangle read by rows: row n lists prime factors of (p^p-1)/(p-1) where p = prime(n).
3

%I #19 Feb 19 2018 22:00:15

%S 3,13,11,71,29,4733,15797,1806113,53,264031,1803647,10949,1749233,

%T 2699538733,109912203092239643840221,461,1289,831603031789,

%U 1920647391913,59,16763,84449,2428577,14111459,58320973,549334763,568972471024107865287021434301977158534824481,149,1999,7993,16651,17317,10192715656759,41903425553544839998158239

%N Triangle read by rows: row n lists prime factors of (p^p-1)/(p-1) where p = prime(n).

%H J. Levine and R. E. Dalton, <a href="http://dx.doi.org/10.1090/S0025-5718-1962-0148604-2">Minimum Periods, Modulo p, of First Order Bell Exponential Integrals</a>, Mathematics of Computation, 16 (1962), 416-423. See Table 3.

%e Triangle begins:

%e [3]

%e [13]

%e [11, 71]

%e [29, 4733]

%e [15797, 1806113]

%e [53, 264031, 1803647]

%e [10949, 1749233, 2699538733]

%e [109912203092239643840221]

%e [461, 1289, 831603031789, 1920647391913]

%e [59, 16763, 84449, 2428577, 14111459, 58320973, 549334763]

%e [568972471024107865287021434301977158534824481]

%e [149, 1999, 7993, 16651, 17317, 10192715656759, 41903425553544839998158239]

%e ...

%p f:=proc(n) local i,t1,p,B,F;

%p p:=ithprime(n);

%p B:=(p^p-1)/(p-1);

%p F:=ifactors(B)[2];

%p lprint(n,p,B,F);

%p t1:=[seq(F[i][1],i=1..nops(F))];

%p sort(t1);

%p end;

%Y Cf. A001039, A054767, A125135, A214810, A214812.

%K nonn,tabf

%O 1,1

%A _N. J. A. Sloane_, Jul 31 2012