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Search: id:A061371
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| A061371 |
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Composite numbers with all prime digits. |
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+0
4
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| 22, 25, 27, 32, 33, 35, 52, 55, 57, 72, 75, 77, 222, 225, 232, 235, 237, 252, 253, 255, 272, 273, 275, 322, 323, 325, 327, 332, 333, 335, 352, 355, 357, 372, 375, 377, 522, 525, 527, 532, 533, 535, 537, 552, 553, 555, 572, 573, 575, 722, 723, 725, 732, 735
(list; graph; listen)
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OFFSET
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0,1
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EXAMPLE
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a(5) = 35 is composite with digits 3 and 5 which are primes.
22 is nonprime and has prime digits, twice 2;
573 is nonprime and has prime digits, 3,5 and 7.
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MAPLE
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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_stnepf:=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))='false') then stpf:=stpf+1; # number of nonprime digits fi od; RETURN(stpf) end:
ts_nepr_neprn0:=proc(n) local i, stpf, ans, ans1, tren; ans:=[ ]: stpf:=0: tren:=1: for i from 1 to n do if ( isprime(i)='false' and ts_stnepf(i) = 0) then ans:=[ op(ans), i ]: tren:=tren+1; fi od; RETURN(ans) end: ts_nepr_neprn0(4000); - Jani Melik (jani_melik(AT)hotmail.com), Apr 11 2004
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CROSSREFS
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Cf. A061372.
Sequence in context: A066737 A121609 A092631 this_sequence A070809 A108632 A045096
Adjacent sequences: A061368 A061369 A061370 this_sequence A061372 A061373 A061374
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KEYWORD
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nonn,base
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AUTHOR
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Amarnath Murthy (amarnath_murthy(AT)yahoo.com), May 02 2001
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EXTENSIONS
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Corrected and extended by Larry Reeves (larryr(AT)acm.org), May 08 2001
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