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A154522 Numbers n such that number of occurrences of the smallest digit in prime(n) is 2.

%I A154522 #12 May 10 2017 03:30:46
%S A154522 5,30,32,36,42,43,47,48,49,50,64,68,71,74,76,84,87,102,130,138,139,
%T A154522 141,151,156,165,169,188,189,191,192,195,196,198,199,202,210,215,216,
%U A154522 218,221,230,233,234,242,248,255,256,257,268,271,282,284,286,293,294,297
%N A154522 Numbers n such that number of occurrences of the smallest digit in prime(n) is 2.
%C A154522 Indices n such that the smallest digit in prime(n), A060420(n), appears twice in the decimal representation of prime(n). [_R. J. Mathar_, Jan 12 2009]
%H A154522 Robert Israel, <a href="/A154522/b154522.txt">Table of n, a(n) for n = 1..10000</a>
%e A154522 If 191=prime(n=43), 1=1 and 1<9, the 43=a(6);
%e A154522 If 199=prime(n=45), then 9=9 and 9>1;
%e A154522 If 211=prime(n=47), 1=1 and 1<2, then 47=a(7);
%e A154522 If 223=prime(n=48), 2=2 and 2<3, then 48=a(48), etc.
%p A154522 A060420 := proc(n) convert(ithprime(n),base,10) ; min(op(%)) ; end: dcount := proc(di,n) local a,d; a := 0 ; convert(n,base,10) ; for d in % do if d = di then a := a+1 ; fi; od; a ; end: isA154522 := proc(n) local d,c ; d := A060420(n) ; c := dcount(d,ithprime(n)) ; RETURN( c = 2 ) ; end: for n from 1 to 800 do if isA154522(n) then printf("%d,",n) ; fi; od: # _R. J. Mathar_, Jan 12 2009
%t A154522 Select[Range[300],Length[Split[Sort[IntegerDigits[Prime[#]]]][[1]]] == 2&] (* _Harvey P. Dale_, Aug 16 2011 *)
%Y A154522 Cf. A000040.
%K A154522 nonn,base
%O A154522 1,1
%A A154522 _Juri-Stepan Gerasimov_, Jan 11 2009
%E A154522 Removed 205, 206, 208. Added 210. _R. J. Mathar_, Jan 12 2009