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%I #17 Mar 24 2024 10:44:23
%S 222,223,225,227,232,233,235,237,252,253,255,257,272,273,275,277,322,
%T 323,325,327,332,333,335,337,352,353,355,357,372,373,375,377,522,523,
%U 525,527,532,533,535,537,552,553,555,557,572,573,575,577,722,723,725
%N Numbers with exactly three prime digits.
%C It is the same as A046034 from two digit numbers from 22 up to four digit numbers from 1222.
%C A193238(a(n))=3; subsequence of A118950. [_Reinhard Zumkeller_, Jul 19 2011]
%H Reinhard Zumkeller, <a href="/A092625/b092625.txt">Table of n, a(n) for n = 1..10000</a>
%e 222 has three prime digits, three times 2;
%e 1235 has three prime digits, 2, 3 and 5.
%p stev_sez:=proc(n) local i, tren, st, ans, anstren; ans:=[ ]: anstren:=[ ]: tren:=n: for i while (tren>0) do st:=round( 10*frac(tren/10) ): ans:=[ op(ans), st ]: tren:=trunc(tren/10): end do; for i from nops(ans) to 1 by -1 do anstren:=[ op(anstren), op(i,ans) ]; od; RETURN(anstren); end: ts_stpf:=proc(n) local i, stpf, ans; ans:=stev_sez(n): stpf:=0: for i from 1 to nops(ans) do if (isprime(op(i,ans))='true') then stpf:=stpf+1; # number of prime digits fi od; RETURN(stpf) end: ts_pr_nt:=proc(n) local i, stpf, ans, ans1, tren; ans:=[ ]: stpf:=0: tren:=1: for i from 1 to n do if ( ts_stpf(i) = 3) then ans:=[ op(ans), i ]: tren:=tren+1; fi od; RETURN(ans) end: ts_pr_nt(2000);
%t Select[Range[800],Total[Boole[PrimeQ[IntegerDigits[#]]]]==3&] (* _Harvey P. Dale_, Dec 31 2023 *)
%o (Haskell)
%o import Data.List (elemIndices)
%o a092625 n = a092625_list !! (n-1)
%o a092625_list = elemIndices 3 a193238_list
%o -- _Reinhard Zumkeller_, Jul 19 2011
%Y Cf. A034895, A046034, A085557, A019546, A034844.
%Y Cf. A084984, A092620, A092624.
%K nonn,base
%O 1,1
%A _Jani Melik_, Apr 11 2004
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