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A092633
Nonprime numbers with exactly three nonprime digits.
0
100, 104, 106, 108, 110, 111, 114, 116, 118, 119, 140, 141, 144, 146, 148, 160, 161, 164, 166, 168, 169, 180, 184, 186, 188, 189, 190, 194, 196, 198, 400, 404, 406, 408, 410, 411, 414, 416, 418, 440, 441, 444, 446, 448, 460, 464, 466, 468, 469, 480, 481
OFFSET
1,1
EXAMPLE
100 is nonprime and has three nonprime digits, twice 0 and 1;
961 is nonprime and has three nonprime digits, 1, 6 and 9.
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_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_neprnt:=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) = 3) then ans:=[ op(ans), i ]: tren:=tren+1; fi od; RETURN(ans) end: ts_nepr_neprnt(1000);
CROSSREFS
Sequence in context: A281149 A204582 A204583 * A213313 A204584 A108343
KEYWORD
nonn,base
AUTHOR
Jani Melik, Apr 11 2004
STATUS
approved