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A108607
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4-almost primes whose sum of factors is a prime.
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5
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40, 54, 56, 88, 90, 104, 136, 184, 198, 210, 248, 250, 294, 296, 328, 350, 376, 390, 414, 424, 462, 488, 522, 536, 550, 570, 584, 664, 686, 714, 776, 798, 808, 824, 850, 856, 858, 930, 950, 954, 1014, 1048, 1062, 1110, 1190, 1208, 1210, 1218, 1256, 1274, 1278
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OFFSET
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1,1
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LINKS
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EXAMPLE
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40=2*2*2*5 (4-almost prime) and 2+2+2+5=11 is a prime.
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PROG
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(PARI) is(n)=my(f=factor(n)); sum(i=1, #f~, f[i, 2])==4 && isprime(sum(i=1, #f~, f[i, 1]*f[i, 2])) \\ Charles R Greathouse IV, Oct 11 2013
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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