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Search: id:A090552
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| A090552 |
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a(1)=1; for n>1, a(n) is the smallest positive integer for which sigma(a(n)) is a multiple of sigma(a(n-1)). |
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+0
2
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| 1, 2, 5, 6, 11, 14, 15, 23, 30, 46, 51, 55, 66, 70, 94, 115, 119, 138, 154, 165, 210, 282, 310, 322, 345, 357, 382, 385, 462, 658, 682, 705, 759, 766, 805, 930, 966, 1146, 1155, 1270, 1426, 1491, 1551, 1581, 1645, 1705, 1771, 1915, 1974, 2046, 2170, 2298, 2415
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OFFSET
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1,2
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EXAMPLE
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After a(4)=6, with sigma(6)=12, the smallest number k such that sigma(k) is a multiple of 12 is 11, with sigma(11)=12. Thus a(5)=11.
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CROSSREFS
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Cf. A090553.
Sequence in context: A045845 A002133 A092306 this_sequence A024520 A015613 A135013
Adjacent sequences: A090549 A090550 A090551 this_sequence A090553 A090554 A090555
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KEYWORD
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nonn
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AUTHOR
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Amarnath Murthy (amarnath_murthy(AT)yahoo.com), Dec 09 2003
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EXTENSIONS
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Corrected, extended, and edited by John W. Layman (layman(AT)math.vt.edu), Aug 10 2004
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