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A079150
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Primes p such that p+1 has at most 3 prime factors, counted with multiplicity; i.e. primes p such that bigomega(p+1) = A001222(p+1) <= 3.
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4
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2, 3, 5, 7, 11, 13, 17, 19, 29, 37, 41, 43, 61, 67, 73, 97, 101, 109, 113, 137, 157, 163, 173, 181, 193, 211, 229, 241, 257, 277, 281, 283, 313, 317, 331, 337, 353, 373, 397, 401, 409, 421, 433, 457, 523, 541, 547, 577, 601, 613, 617, 641, 653, 661, 673, 677
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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EXAMPLE
| 173 is in the sequence because 173+1 = 2*3*29 has 3 prime factors.
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MATHEMATICA
| Select[Prime[Range[200]], PrimeOmega[#+1]<4&] (* From Harvey P. Dale, Feb 02 2012 *)
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PROG
| (PARI) s(n) = {sr=0; ct=0; forprime(x=2, n, if(bigomega(x+1) < 4, print1(x" "); sr+=1.0/x; ct+=1; ); ); print(); print(ct" "sr); } \\ Lists primes p<=n such that p+1 has at most 3 prime factors.
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CROSSREFS
| Cf. A079147, A079151, A079152, A079153.
Sequence in context: A119615 A061771 A124589 * A177000 A117843 A068192
Adjacent sequences: A079147 A079148 A079149 * A079151 A079152 A079153
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KEYWORD
| easy,nonn,changed
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AUTHOR
| Cino Hilliard (hillcino368(AT)gmail.com), Dec 27 2002
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