A107077 Odd-digit products of three odd-digit primes p*q*r.

75, 99, 117, 153, 171, 175, 195, 333, 357, 399, 531, 539, 555, 595, 711, 715, 775, 777, 795, 931, 935, 1113, 1179, 1331, 1359, 1519, 1533, 1557, 1573, 1719, 1737, 1773, 1775, 1791, 1975, 3171, 3177, 3179, 3357, 3395, 3515, 3553, 3573, 3577, 3751, 3757, 3759

Offset

1,1

Comments

Odd-digit primes p,q,r are not necessarily all different, e.g. 75=3*5*5, 99=3*3*11, 1533=3*7*73, etc. Cf. A107076: Odd-digit semiprimes divisors of which are odd-digit primes.

Links

Charles R Greathouse IV, Table of n, a(n) for n = 1..10000

Mathematica

With[{odps=Select[Prime[Range[100]], And@@OddQ[IntegerDigits[#]]&]}, Union[Select[Times@@@Tuples[odps, 3], And@@OddQ[IntegerDigits[#]]&]]] (* Harvey P. Dale, Feb 02 2012 *)

Prog

(PARI) D=[0, 2, 4, 6, 8];
oddDigits(n)=#setintersect(Set(digits(n)), D)==0
list(lim)=my(v=List(), P=v, L=lim\3, pq, t); forprime(p=3, L\3, if(oddDigits(p), listput(P, p))); P=Vec(P); for(i=1, #P, for(j=1, i, pq=P[i]*P[j]; if(pq>L, break); for(k=1, j, t=pq*P[k]; if(t>lim, break); if(oddDigits(t), listput(v, t))))); P=0; Set(v) \\ Charles R Greathouse IV, Feb 15 2017

Crossrefs

Cf. A107076.

Sequence in context: A247272 A272023 A286353 * A039485 A226475 A337251

Adjacent sequences: A107074 A107075 A107076 * A107078 A107079 A107080

Keyword

nonn,base

Author

Zak Seidov, May 10 2005

Extensions

Corrected and extended by Harvey P. Dale, Feb 02 2012

Status

approved