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Search: id:A158377
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| 0, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 10, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 14, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 15, 61, 62, 63, 64, 65, 22, 67, 68, 69, 14, 71, 72
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OFFSET
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1,2
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COMMENT
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a(n) for n >= 2 equals LCM of minimal and maximal prime power factors in prime factorization of n. For n >= 2 holds: a(n)*A100994(n) = A034684(n)*A034699(n). a(n) for n >= 2 it deviates from A000027(n), first different term is a(30)=a(2*3*5), a(30)=LCM(2,5)=10, A000027(30)= 30. Sequence of deviations from A000027(n):30,42,60,66,70,78,84,90,...
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FORMULA
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a(1) = 0, a(p) = p, a(pq) = pq, a(pq...z) = pz, a(p^k) = p^k, for p = primes (A000040), pq = product of two distinct primes (A006881), pq...z = product of k (k > 2) distinct primes p, q, ..., z (A120944), p^k = prime powers (A000961(n) for n > 1), k = natural numbers (A000027).
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EXAMPLE
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For n=30=2*3*5 the a(30)=LCM(2,5)=10.
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CROSSREFS
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Cf.: A100994, A034684, A034699, A000027.
Sequence in context: A137317 A094759 A030542 this_sequence A008684 A138202 A056064
Adjacent sequences: A158374 A158375 A158376 this_sequence A158378 A158379 A158380
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KEYWORD
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nonn
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AUTHOR
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Jaroslav Krizek (jaroslav.krizek(AT)atlas.cz), Mar 17 2009
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