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Search: id:A133564
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| A133564 |
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a(1)=1. a(n+1) = sum{k=isolated divisors of n} a(k). An isolated divisor, k, of n is a positive divisor of n where neither (k-1) nor (k+1) divides n. |
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+0
2
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| 1, 1, 0, 1, 1, 2, 2, 3, 4, 5, 6, 7, 9, 10, 12, 14, 18, 19, 25, 26, 31, 34, 40, 41, 53, 55, 64, 69, 82, 83, 100, 101, 119, 126, 144, 148, 180, 181, 206, 216, 250, 251, 292, 293, 334, 352, 392, 393, 460, 463, 522, 541, 606, 607, 696, 704, 784, 810, 892, 893, 1026, 1027, 1127
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OFFSET
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1,6
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EXAMPLE
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The positive divisors of 20 are 1,2,4,5,10,20. Of these, 1 and 2 are adjacent, and 4 and 5 are adjacent. So the isolated divisors of 20 are 10 and 20. Therefore a(21) = a(10) + a(20) = 5 + 26 = 31.
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CROSSREFS
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Cf. A133565.
Sequence in context: A065459 A011873 A008673 this_sequence A017863 A088567 A029014
Adjacent sequences: A133561 A133562 A133563 this_sequence A133565 A133566 A133567
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KEYWORD
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nonn
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AUTHOR
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Leroy Quet (q1qq2qqq3qqqq(AT)yahoo.com), Sep 16 2007
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EXTENSIONS
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Extended by Ray Chandler (rayjchandler(AT)sbcglobal.net), Jun 25 2008
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