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A165303
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a(n) is the smallest number not already in the sequence, such that the concatenation of all a(n) displays the periodic digit string 1, 2, 3, 4, 5 (and repeat).
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3
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1, 2, 3, 4, 5, 12, 34, 51, 23, 45, 123, 451, 234, 512, 345, 1234, 5123, 4512, 3451, 2345, 12345, 123451, 23451, 234512, 34512, 345123, 45123, 451234, 51234, 512345, 1234512, 3451234, 5123451, 2345123, 4512345, 12345123, 45123451, 23451234, 51234512
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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EXAMPLE
| Starting from 1, 2, 3, 4, 5, the next number must be 12 because we need to continue with a 1. But 1 is already in the sequence so we need to attach a 2 -> 12. And so on.
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MAPLE
| cyc5 := proc(n) op(n, [2, 3, 4, 5, 1]) ; end:
A165303 := proc(n) option remember ; local k, prev, d, a ; if n = 1 then 1; else d := cyc5(procname(n-1) mod 10) ; a := d ; while true do prev := false; for k from 1 to n-1 do if procname(k) = a then prev := true; break; end if; end do; if not prev then return a; end if; d := cyc5(d) ; a := 10*a+d ; end do; end if ; end proc:
seq(A165303(n), n=1..60) ; # R. J. Mathar, Oct 16 2009
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CROSSREFS
| A165300-A165302, A165304-A165307
Sequence in context: A109849 A007662 A175807 * A109744 A065635 A101546
Adjacent sequences: A165300 A165301 A165302 * A165304 A165305 A165306
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KEYWORD
| easy,base,nonn
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AUTHOR
| Paolo P. Lava & Giorgio Balzarotti (paoloplava(AT)gmail.com), Sep 14 2009
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EXTENSIONS
| Keyword:base added, sequence extended by R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Oct 16 2009
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