A348370 - OEIS

%I #13 Dec 10 2023 14:28:56

%S 1,2,3,4,5,12,21,86,235,8114118,535252535

%N Numbers k such that pi(reversal(prime(k))) = reversal(k). Ignore leading 0's.

%C 535252535 is a term (not necessarily the next one), so it seems this sequence is a supersequence of A069469.

%C From _Martin Ehrenstein_, Nov 06 2021: (Start)

%C Equivalently: Numbers k such that prime(reversal(k)) <= reversal(prime(k)) < prime(reversal(k)+1). Ignore leading 0's.

%C Thus A069469 is indeed a subsequence.

%C a(12) > 10^10. (End)

%t Select[Range[300],PrimePi[IntegerReverse[Prime[#]]]==IntegerReverse[#]&]

%Y Cf. A000040, A000720, A004086, A069469.

%K nonn,base,more

%O 1,2

%A _Ivan N. Ianakiev_, Oct 15 2021

%E a(11) verified by _Martin Ehrenstein_, Nov 06 2021