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%I #15 Jan 05 2025 23:39:44
%S 3,4,12,30,33,1406
%N Numbers k such that reverse(A004154(k)) - 1 is prime.
%C The values corresponding to a(1)-a(6) have been certified prime with Primo. a(7) > 15000. - _Giovanni Resta_, Feb 20 2013
%C a(7) > 40000. - _Michael S. Branicky_, Jan 05 2025
%t f[n_] := n!/10^Sum[Floor[n/5^k], {k, 1, Log[10, n] + 1}]; Do[ If[ PrimeQ[ FromDigits[ Reverse[ IntegerDigits[ f[n]]]] - 1], Print[n]], {n, 1, 800}]
%Y Cf. A078305, A004154.
%K base,more,nonn
%O 1,1
%A _Jason Earls_ and _Robert G. Wilson v_, Dec 27 2002
%E a(6) from _Giovanni Resta_, Feb 20 2013