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A092625 Numbers with exactly three prime digits. 5
222, 223, 225, 227, 232, 233, 235, 237, 252, 253, 255, 257, 272, 273, 275, 277, 322, 323, 325, 327, 332, 333, 335, 337, 352, 353, 355, 357, 372, 373, 375, 377, 522, 523, 525, 527, 532, 533, 535, 537, 552, 553, 555, 557, 572, 573, 575, 577, 722, 723, 725 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

It is the same as A046034 from two digit numbers from 22 up to four digit numbers from 1222.

A193238(a(n))=3; subsequence of A118950. [Reinhard Zumkeller, Jul 19 2011]

LINKS

Reinhard Zumkeller, Table of n, a(n) for n = 1..10000

EXAMPLE

222 has three prime digits, three times 2;

1235 has three prime digits, 2, 3 and 5.

MAPLE

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);

PROG

(Haskell)

import Data.List (elemIndices)

a092625 n = a092625_list !! (n-1)

a092625_list = elemIndices 3 a193238_list

-- Reinhard Zumkeller, Jul 19 2011

CROSSREFS

Cf. A034895, A046034, A085557, A019546, A034844.

Cf. A084984, A092620, A092624.

Sequence in context: A083959 A078212 A078251 * A043612 A101955 A063352

Adjacent sequences:  A092622 A092623 A092624 * A092626 A092627 A092628

KEYWORD

nonn,base

AUTHOR

Jani Melik, Apr 11 2004

STATUS

approved

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Last modified June 24 09:56 EDT 2017. Contains 288697 sequences.