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Search: id:A005348
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| A005348 |
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Number of ways to add n ordinals.
(Formerly M1435)
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+0
1
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| 1, 2, 5, 13, 33, 81, 193, 449, 1089, 2673, 6561, 15633, 37249, 88209, 216513, 531441, 1266273, 3017169, 7189057, 17537553, 43046721, 102568113, 244390689, 582313617
(list; graph; listen)
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OFFSET
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1,2
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REFERENCES
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N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
Wakulicz, A. Sur la somme d'un nombre fini de nombres ordinaux. Fund. Math. 36 (1949), 254-266; 38 (1951), 239.
P. Erdos, Some remarks on set theory, Proc. Am. Math. Soc. 1 (1950) 127-141.
W. Sierpinski, Cardinal and Ordinal Numbers, 2nd ed. p 275.
R. K. Guy, The second strong law of small numbers. Math. Mag. 63 (1990), no. 1, 3-20.
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LINKS
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Eric Weisstein's World of Mathematics, Link to a section of The World of Mathematics.
A. Wakulicz, Sur la somme d'un nombre fini de nombres ordinaux, Fund. Math. 36 (1949), 254-266.
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FORMULA
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a(n)=81*a(n-5) for n >= 21.
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CROSSREFS
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Sequence in context: A001659 A088921 A005183 this_sequence A067676 A116703 A116724
Adjacent sequences: A005345 A005346 A005347 this_sequence A005349 A005350 A005351
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KEYWORD
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nonn,easy
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AUTHOR
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N. J. A. Sloane (njas(AT)research.att.com), R. K. Guy, Bill Sands and Tommy Kucera.
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