cp's OEIS Frontend

A295206 Number of primes that are permutations of the first 3*n - 2 numbers.

%I A295206 #28 Jan 12 2018 05:55:39
%S A295206 0,4,534,222864,284197799
%N A295206 Number of primes that are permutations of the first 3*n - 2 numbers.
%C A295206 The sequence would be a concatenation of chunks of the form {x, 0, 0}, where x is a value greater than zero, apart from the first term. Here only x's are listed.
%e A295206 a(2) = 4 because for the first 4 numbers {1,2,3,4} we have 1423, 2143, 2341, 4231 that are prime.
%p A295206 with(combinat): P:=proc(q) local a,b,j,k,n,t; a:=[];
%p A295206 for n from 1 to q do a:=permute(3*n-2); t:=0;
%p A295206 for k from 1 to nops(a) do b:=0;
%p A295206 for j from 1 to nops(a[k]) do b:=10^(ilog10(a[k][j])+1)*b+a[k][j]; od;
%p A295206 if isprime(b) then t:=t+1; fi; od; print(t);
%p A295206 od; end: P(5); # _Paolo P. Lava_, Nov 17 2017
%t A295206 Array[Count[Map[FromDigits@ Flatten[IntegerDigits@ #] &, Permutations[Range@ #, {#}]], _?PrimeQ] &, 10] (* _Michael De Vlieger_, Nov 17 2017 *)
%Y A295206 Cf. A000040, A175429.
%K A295206 nonn,base,more,hard
%O A295206 1,2
%A A295206 _Paolo P. Lava_, Nov 17 2017
%E A295206 a(4)-a(5) from _Giovanni Resta_, Nov 17 2017