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Search: id:A137945
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| A137945 |
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Non-prime-powers such that the number of composite divisors is a multiple of the number of prime divisors. |
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+0
3
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| 36, 100, 120, 144, 168, 196, 225, 264, 270, 280, 312, 324, 378, 400, 408, 440, 441, 456, 484, 520, 552, 576, 594, 616, 676, 680, 696, 702, 728, 744, 750, 760, 784, 888, 918, 920, 945, 952, 960, 984, 1026, 1032, 1064, 1089, 1128, 1144, 1156, 1160, 1225, 1240
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OFFSET
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1,1
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COMMENT
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A055212(a(n)) mod A001221(a(n)) = 0; intersection of A024619 and A137944.
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LINKS
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R. Zumkeller, Table of n, a(n) for n = 1..1000
Eric Weisstein's World of Mathematics, Divisor Function
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EXAMPLE
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A055212(120) = #{4,6,8,10,12,15,20,24,30,40,60,120} = 12 = 4*A001221(120) = 4*#{2,3,5} = 12, therefore 120 is a term.
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CROSSREFS
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Sequence in context: A057392 A118632 A114819 this_sequence A072413 A131605 A063734
Adjacent sequences: A137942 A137943 A137944 this_sequence A137946 A137947 A137948
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KEYWORD
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nonn
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AUTHOR
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Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Feb 24 2008
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