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A110228
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4-almost primes p * q * r * s not relatively prime to p + q + r + s.
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12
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16, 24, 36, 60, 81, 84, 100, 126, 132, 140, 150, 156, 196, 204, 220, 228, 234, 260, 276, 308, 315, 330, 340, 342, 348, 364, 372, 375, 380, 444, 460, 476, 484, 490, 492, 495, 510, 516, 525, 532, 558, 564, 572, 580, 585, 620, 625, 636, 644, 650, 666, 676, 690
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OFFSET
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1,1
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COMMENTS
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p, q, r, s are not necessarily distinct. The converse to this is A110227: 4-almost primes p * q * r * s which are relatively prime to p+q+r+s.
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LINKS
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EXAMPLE
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84 is in this sequence because 84 = 2^2 * 3 * 7 and the sum of these prime factors is 2 + 2 + 3 + 7 = 14 = 2 * 7, which is a divisor of 84.
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PROG
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(PARI) list(lim)=my(v=List()); forprime(p=2, lim\8, forprime(q=2, min(p, lim\4\p), my(pq=p*q); forprime(r=2, min(lim\pq\2, q), my(pqr=pq*r, t); forprime(s=2, min(lim\pqr, r), t=pqr*s; if(gcd(t, p+q+r+s)>1, listput(v, t)))))); Set(v) \\ Charles R Greathouse IV, Jan 31 2017
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CROSSREFS
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Cf. A014613, A110187, A110188, A110227, A110229, A110230, A110231, A110232, A110289, A110290, A110296, A110297.
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KEYWORD
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easy,nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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