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A035479
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(-1)sigma sequence: a(n)=(-1)sigma(a(n-1)), where if x=Product p(i)^r(i), then (-1)sigma(x)=Product(-1+(Sum p(i)^s(i), s(i)=1 to r(i))).
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0
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624, 696, 728, 936, 1716, 1200, 1682, 869, 780, 480, 488, 780, 480, 488, 780, 480, 488, 780, 480, 488
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OFFSET
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0,1
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COMMENTS
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This sequence becomes a cycle of period 3: 780, 480, 488. It is called (-1)sigma sociable of order 3.
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LINKS
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Table of n, a(n) for n=0..19.
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EXAMPLE
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Factorizations: 2^4*3*13,2^3*3*29,2^3*7*13,2^3*3^2*13,2^2*3*11*13, 2^4*3*5^2,2*29^2,11*79,2^2*3*5*13,2^5*3*5,2^3*61
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CROSSREFS
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Sequence in context: A283898 A345546 A345799 * A180453 A216843 A043368
Adjacent sequences: A035476 A035477 A035478 * A035480 A035481 A035482
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KEYWORD
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nonn
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AUTHOR
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Yasutoshi Kohmoto
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STATUS
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approved
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