This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A248856 #29 May 27 2018 01:39:01 %S A248856 1,853,91182,926756,9374193,94535668,951496285,9563906973, %T A248856 963706466000,9665127969899,96891533076641,970995550452370, %U A248856 9728143518403637,97441817594570206,975843062833251485,9771174122943813068 %N A248856 Numbers n such that n + pi(n) is a power of 10. %C A248856 Numbers n such that pi(n) equals 10^ceiling(log(10,n)) - n. %C A248856 853 is the only known prime term of the sequence. If n is a prime term of the sequence and m = pi(n) then prime(m) + m is a power of 10. So 147 = pi(853) is the only known number m such that prime(m) + m is a power of 10. What is the next such number? %C A248856 For each number n there exists at most one n-digit term. %C A248856 a(11) = 96891533076641 is also prime. - _Chai Wah Wu_, May 25 2018 %e A248856 pi(96891533076641) + 96891533076641 = 10^14 so 96891533076641 is in the sequence. %t A248856 Select[Range[1000], IntegerQ[Log[10, # + PrimePi[#]]] &] (* _Alonso del Arte_, Dec 31 2014 *) %o A248856 (PARI) for(n=1,10^3,s=digits(n+primepi(n)-1);if(s==[]||vecmin(s)==9,print1(n,", "))) \\ _Derek Orr_, Jan 02 2015 %Y A248856 Cf. A000720, A244440, A248854. %K A248856 nonn,hard %O A248856 1,2 %A A248856 _Farideh Firoozbakht_, Dec 31 2014 %E A248856 a(12)-a(16) from _Chai Wah Wu_, May 25 2018