Search: id:A100414
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%I A100414
%S A100414 21,48034,69926,180461,214591,409473,563715,41630193,253385633342,
%T A100414 661494322636
%N A100414 Numbers n such that n is R(n)-th composite number where R(n) is the digit 
               reversal of n (A002808(A004086(n))=n).
%C A100414 There is no further term < 3*10^9.
%C A100414 a(11) > 3*10^12. [From Donovan Johnson (donovan.johnson(AT)yahoo.com), 
               Jun 14 2009]
%e A100414 41630193 is in the sequence because 41630193 is 39103614-th composite 
               number.
%t A100414 Do[s=FromDigits[Reverse[IntegerDigits[n]]];If[s<n&&!PrimeQ[n] &&s==n-PrimePi[n]-1, 
               Print[n]], {n, 2, 42000000}]
%Y A100414 Cf. A002808, A004086, A100412, A100413, A100415.
%Y A100414 Sequence in context: A167063 A115485 A001167 this_sequence A068735 A013768 
               A143736
%Y A100414 Adjacent sequences: A100411 A100412 A100413 this_sequence A100415 A100416 
               A100417
%K A100414 base,more,nonn
%O A100414 1,1
%A A100414 Farideh Firoozbakht (mymontain(AT)yahoo.com), Dec 10 2004
%E A100414 a(9)-a(10) from Donovan Johnson (donovan.johnson(AT)yahoo.com), Jun 14 
               2009

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