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A074908
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Number of integers with an odd number of distinct primes (for which mu(n)=-1) between two consecutive primes prime(n) and prime(n+1).
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0
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2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 2, 2, 3, 2, 2, 2, 2, 3, 3, 2, 3, 2, 2, 2, 2, 3, 3, 2, 3, 3, 3, 2, 3, 2, 2, 3, 2, 3, 3, 3, 2, 5, 2, 3, 2, 2, 3, 2, 2, 4, 3, 2, 3, 3, 3, 3, 2, 3, 2, 3, 5, 2, 3, 2, 2, 4, 2, 3, 2, 2, 4, 3, 3, 3, 2, 3, 2, 3, 4, 4, 2, 5, 2, 5, 3, 2, 3, 2, 2, 3, 4, 3, 2, 4, 2, 3, 3, 2, 4, 2, 3, 3, 2, 2, 3
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,1
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EXAMPLE
| Between 7919 and 7927 the 5 numbers which have an odd number of distinct primes are as follows: {7919,7922,7923,7926,7927}, so a(1000)=5.
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MAPLE
| readlib(issqr): lstmp := proc(n) local t1, i; t1 := 0; for i from ithprime(n) to ithprime(n+1) do if (issqrfree(i) = 'true' and mobius(i)=-1) then t1 := t1+1; fi; od; t1; end: lstmp(200);
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CROSSREFS
| Cf. A061265, A061399.
Sequence in context: A103663 A083311 A037968 * A151963 A191291 A171622
Adjacent sequences: A074905 A074906 A074907 * A074909 A074910 A074911
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KEYWORD
| nonn
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AUTHOR
| Jani Melik (jani_melik(AT)hotmail.com), Sep 30 2002
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