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 A046942 Numbers n such that n and prime(n) are both palindromes. 7
 1, 2, 3, 4, 5, 8114118, 535252535 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Previous name: Indices of primes appearing in A046941. Also, intersection of A002113 and A075807. - Ivan Neretin, Jun 02 2016 LINKS Eric Weisstein's World of Mathematics, Palindromic Prime MATHEMATICA NextPalindrome[n_] := Block[ {l = Floor[ Log[10, n] + 1], idn = IntegerDigits[n]}, If[ Union[ idn] == {9}, Return[n + 2], If[l < 2, Return[n + 1], If[ FromDigits[ Reverse[ Take[ idn, Ceiling[l/2]]]] FromDigits[ Take[ idn, -Ceiling[l/2]]], FromDigits[ Join[ Take[ idn, Ceiling[l/2]], Reverse[ Take[ idn, Floor[l/2]]] ]], idfhn = FromDigits[ Take[ idn, Ceiling[l/2]]] + 1; idp = FromDigits[ Join[ IntegerDigits[ idfhn], Drop[ Reverse[ IntegerDigits[ idfhn]], Mod[l, 2]]]] ]]]]; p = 0; Do[p = NextPalindrome[p]; While[ !PrimeQ[p], p = NextPalindrome[ p]]; q = IntegerDigits[ PrimePi[ p]]; If[Reverse[q] == q, Print[{p, FromDigits[q]}]], {n, 10^4}] (* Robert G. Wilson v, Feb 03 2005 *) CROSSREFS Equals pi(A046941). Cf. A046941, A103357, A103358, A103402, A103403. Sequence in context: A004911 A062934 A038106 * A051703 A004567 A030378 Adjacent sequences:  A046939 A046940 A046941 * A046943 A046944 A046945 KEYWORD nice,nonn,base AUTHOR EXTENSIONS a(7) from Giovanni Resta, May 14 2003 New name and offset by Ivan Neretin, Jun 02 2016 STATUS approved

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Last modified February 21 09:51 EST 2018. Contains 299390 sequences. (Running on oeis4.)