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
Links
- Charles R Greathouse IV, Table of n, a(n) for n = 1..10000
Crossrefs
Cf. A107076.
Programs
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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 *) -
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
Extensions
Corrected and extended by Harvey P. Dale, Feb 02 2012
Comments