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A102300
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Number of distinct prime divisors of n where n and n+1 are composite or twin composite numbers.
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0
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1, 1, 2, 2, 2, 2, 2, 1, 2, 1, 1, 2, 2, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2, 2, 2, 2, 2, 2, 1, 3, 2, 2, 2, 3, 2, 2, 2, 2, 2, 2, 2, 2, 3, 3, 2, 3, 2, 2, 2, 2, 2, 3, 1, 2, 2, 2, 1, 1, 2, 3, 2, 2, 2, 3, 2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 2, 2, 2, 2, 2, 2, 3, 3, 1, 3, 2, 3, 2, 2, 2, 3, 2, 2, 2, 3, 2, 2
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,3
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EXAMPLE
| For n=8 n+1=9 a twin composite pair. 8=2^3 has 1 distinct divisor, 2.
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PROG
| (PARI) f2(n) = for(x=1, n, y=composite(x); if(!isprime(y+1), print1(omega(y)", "))) composite(n) =\The n-th composite number. 1 is def as not prime nor composite. { local(c, x); c=1; x=1; while(c <= n, x++; if(!isprime(x), c++); ); return(x) }
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CROSSREFS
| Sequence in context: A159700 A083534 A174664 * A202146 A087010 A098220
Adjacent sequences: A102297 A102298 A102299 * A102301 A102302 A102303
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KEYWORD
| easy,nonn
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AUTHOR
| Cino Hilliard (hillcino368(AT)gmail.com), Feb 19 2005
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