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%I #16 Jan 31 2013 16:48:48
%S 1,4,25,149,1101,8489,69978,596022,5179467,45811178
%N Number of primes of the form (x+1)^5 - x^5 with x <= 10^n.
%C Number of primes equal to the difference of two consecutive fifth powers (x+1)^5 - x^5 = 5x(x+1)(x^2+x+1)+1 (A121616) with x <= 10^n. Values of x = A121617. Sequence of number of primes of the form (x+1)^5 - x^5 with x <= 10^n have similar characteristics to similar sequences for natural primes and cuban primes (A221794).
%t fQ[n_] := PrimeQ[(n + 1)^5 - n^5]; c = k = 0; Do[ While[k < 10^n + 1, If[ fQ@ k, c++]; k++]; Print[{n, c}], {n, 9}] (* _Robert G. Wilson v_, Jan 31 2013 *)
%K nonn,base
%O 0,2
%A _Vladimir Pletser_, Jan 26 2013
%E a(7) - a(9) from _Robert G. Wilson v_, Jan 31 2013
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