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Search: id:A072890
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| A072890 |
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The 28-cycle of the n => sigma(n)-n process, where sigma(n) is the sum of divisors of n (A000203). |
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+0
4
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| 14316, 19116, 31704, 47616, 83328, 177792, 295488, 629072, 589786, 294896, 358336, 418904, 366556, 274924, 275444, 243760, 376736, 381028, 285778, 152990, 122410, 97946, 48976, 45946, 22976, 22744, 19916, 17716, 14316
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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Called a "sociable" chain.
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REFERENCES
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P. Poulet, Parfaits, amiables et extensions, Editions Stevens, Bruxelles, 1918.
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FORMULA
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a(28+n)=a(n).
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MATHEMATICA
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f[n_]:=Plus@@Divisors[n]-n; a=7524; Table[a=f[a], {n, 0, 28}] [From Vladimir Orlovsky (4vladimir(AT)gmail.com), Nov 01 2009]
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CROSSREFS
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Cf. A000203, A045477, A072891.
Sequence in context: A115554 A106726 A064965 this_sequence A049442 A106725 A144649
Adjacent sequences: A072887 A072888 A072889 this_sequence A072891 A072892 A072893
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KEYWORD
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fini,full,nonn,new
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AUTHOR
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Miklos Kristof (kristmikl(AT)freemail.hu), Jul 29 2002
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