cp's OEIS Frontend

A281577 Irregular triangle read by rows: T(n, k) = A281576(n) modulo p^2, where p is the k-th prime factor of A281576(n) with p < sqrt(A281576(n)).

%I A281577 #19 Feb 03 2017 21:53:43
%S A281577 28204,17161560961,2451293172821355028751076998879853,
%T A281577 1409441895293467096954080352837,1385195550582,
%U A281577 17782786311867894562037823351528977990025091057921642664123352687840735480821116989430796689072791
%N A281577 Irregular triangle read by rows: T(n, k) = A281576(n) modulo p^2, where p is the k-th prime factor of A281576(n) with p < sqrt(A281576(n)).
%C A281577 The question whether T(n, k) = 0 for any values of n and k is an open problem (see Ribenboim p. 64, open problem (3)).
%D A281577 P. Ribenboim, The Little Book of Bigger Primes, Springer Verlag, 1991.
%e A281577 Triangle T(n, k) starts
%e A281577                                   28204
%e A281577                             17161560961
%e A281577      2451293172821355028751076998879853
%e A281577         1409441895293467096954080352837
%e A281577                  1385195550582, T(5, 2)
%e A281577 Note: T(5, 2) is not displayed here due to its size. The term can be seen in the Data section.
%o A281577 (PARI) a152155(n) = centerlift(Mod(3, 2^(2^n)+1)^(2^(2^n-1)))
%o A281577 row(n) = my(i=0, k=1); while(1, if(a152155(k)!=-1, i++); if(i==n, forprime(p=1, sqrtint(2^(2^k)+1), if(Mod(2, p)^(2^k)==-1, print1(lift(Mod(2, p^2)^(2^k))+1, ", ")))); k++)
%o A281577 trianglerows(n) = for(k=1, n, row(k); print(""))
%Y A281577 Cf. A050922, A281576.
%K A281577 nonn,tabf
%O A281577 1,1
%A A281577 _Felix Fröhlich_, Jan 24 2017