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A053063
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Alternately append n to beginning or end of previous term.
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0
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1, 21, 213, 4213, 42135, 642135, 6421357, 86421357, 864213579, 10864213579, 1086421357911, 121086421357911, 12108642135791113
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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REFERENCES
| Felice Russo, A set of new Smarandache functions, sequences and conjectures in number theory, American Research Press 2000
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LINKS
| M. L. Perez et al., eds., Smarandache Notions Journal
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FORMULA
| a(n)=(1/2)*(1+(-1)^n)*(n*10^(floor(1+log10(a(n-1))))+a(n-1))+(1/2)*(1-(-1)^n)*(a(n-1)*10^(floor(1+log10(n)))+n), with a(0)=1 [From Paolo P. Lava (paoloplava(AT)gmail.com), Oct 29 2008]
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MAPLE
| P:=proc(i) local a, n; a:=1; print(a); for n from 2 by 1 to i do a:=1/2*(1+(-1)^n)*(n*10^trunc(evalf(floor(1+log10(a)), 100))+a)+1/2*(1-(-1)^n)*(a*10^trunc(evalf(floor(1+log10(n)), 100))+n); print(a); od; end: P(100); [From Paolo P. Lava (paoloplava(AT)gmail.com), Oct 29 2008]
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CROSSREFS
| Sequence in context: A133355 A041846 A120786 * A060933 A075282 A165223
Adjacent sequences: A053060 A053061 A053062 * A053064 A053065 A053066
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KEYWORD
| easy,nonn,base
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AUTHOR
| Felice Russo (frusso(AT)micron.com), Feb 25 2000
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