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Search: id:A137741
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| A137741 |
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Number of different strings of length n+4 obtained from "123...n" by iteratively duplicating any substring. |
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+0
3
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| 1, 16, 54, 119, 218, 360, 555, 814, 1149, 1573, 2100, 2745, 3524, 4454, 5553, 6840, 8335, 10059, 12034, 14283
(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 for n=1,2; a(n)=1/24*(n+3)*(n^3+15*n^2+50*n-96) for n>2 (conjectured).
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PROGRAM
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(PARI) A137741(n)=if(n<2, 1, n=A135473(n+4, n); n[ #n]) /* function A135473 defined in A137743 */
(PARI) A137741(n)=if(n<3, n^4, 1/24*(n+3)*(n^3+15*n^2+50*n-96)) /* conjectured */
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CROSSREFS
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Cf. A137740-A137743, A135473, A137744-A137748.
Sequence in context: A117273 A137515 A164324 this_sequence A167690 A122658 A152096
Adjacent sequences: A137738 A137739 A137740 this_sequence A137742 A137743 A137744
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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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