A235693 Semiprimes which have one or more occurrences of exactly five different digits.

10237, 10238, 10239, 10249, 10265, 10279, 10294, 10297, 10327, 10342, 10345, 10347, 10349, 10358, 10367, 10378, 10379, 10389, 10394, 10397, 10423, 10435, 10462, 10473, 10483, 10489, 10493, 10495, 10497, 10523, 10537, 10543, 10546, 10547, 10562, 10573, 10579

Offset

1,1

Comments

The first term having a repeated digit is 100235.

The first term that is a square is 12769. - Robert Israel, Jul 06 2018

Links

Robert Israel, Table of n, a(n) for n = 1..6240

Maple

# to get all terms with 5 digits S:= combinat:-choose([$0..9], 5):
f:= proc(x) local s, L;
      L:= convert(x, base, 5);      if nops(L) < 5 then L:= [op(L), 0$(5-nops(L))] fi;      if nops(convert(L, set))<5 then return NULL fi;
      op(select(t -> t > 10^4 and numtheory:-bigomega(t)=2, map(s -> add(s[L[i]+1]*10^(i-1), i=1..5), S)))
end proc:
sort(map(f, [$1..5^5-1])); # Robert Israel, Jul 06 2018

Mathematica

Select[Range[10000, 11000], PrimeOmega[#]==2&&Count[DigitCount[#], 0]==5&] (* Harvey P. Dale, Apr 08 2015 *)

Prog

(PARI)
list(lim)=my(v=List(), t); forprime(p=2, sqrt(lim), t=p; forprime(q=p, lim\t, listput(v, t*q))); vecsort(Vec(v)) \\ From A001358
b=list(15000); s=[]; for(n=1, #b, if(#vecsort(eval(Vec(Str(b[n]))), , 8)==5, s=concat(s, b[n]))); s

Crossrefs

Cf. A235690-A235692, A235694-A235696.

Cf. A235154-A235161.

Sequence in context: A183743 A236743 A031987 * A247948 A254563 A074671

Adjacent sequences: A235690 A235691 A235692 * A235694 A235695 A235696

Keyword

nonn,base

Author

Colin Barker, Jan 14 2014

Status

approved