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Search: id:A137740
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| A137740 |
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Number of different strings of length n+5 obtained from "123...n" by iteratively duplicating any substring. |
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+0
12
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| 1, 32, 138, 348, 700, 1246, 2050, 3188, 4749, 6836, 9567, 13076, 17514, 23050, 29872, 38188, 48227, 60240, 74501, 91308
(list; graph; listen)
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OFFSET
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1,2
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COMMENT
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See A137743 for comments and examples.
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LINKS
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Index entries for doubling substrings
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FORMULA
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a(n)=(n+4)(n^2+3n-8)(n^2+23n+150)/5!+4 for n>4.
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PROGRAM
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(PARI) A137740(n)=if(n<2, 1, n=A135473(n+5, n); n[ #n]) /* function A135473 defined in A137743 */
(PARI) A137740(n)=if(n>4, n*(n*(n*(n*(n+30)+315)+1110)-136)/5!-36, [1, 32, 138, 348][n])
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CROSSREFS
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Cf. A137739-A137743, A135473, A137744-A137748.
Sequence in context: A060670 A044364 A044745 this_sequence A100164 A048191 A097199
Adjacent sequences: A137737 A137738 A137739 this_sequence A137741 A137742 A137743
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KEYWORD
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nonn
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AUTHOR
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M. F. Hasler (MHasler(AT)univ-ag.fr), Feb 10 2008
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