A092633 Nonprime numbers with exactly three nonprime digits.

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

Links

Table of n, a(n) for n=1..51.

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

Adjacent sequences: A092630 A092631 A092632 * A092634 A092635 A092636

Keyword

nonn,base

Author

Jani Melik, Apr 11 2004

Status

approved