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A077293
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Partition the concatenation 1234567...of natural numbers into successive strings nontrivially (a(n) is not equal to n) such that the n-th string is a multiple of n.
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15
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12, 34, 567, 8, 910, 111213141516, 17181920, 2122232425262728, 293031, 323334353637383940, 41424344454647, 48, 49505152535455565758596061626364, 6566, 676869707172737475, 767778798081828384, 85, 868788
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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COMMENTS
| a(1) = 12, a(n) = smallest concatenation of next successive natural numbers that is a multiple of n, or 0 if no such concatenation exists.
a(1) = 1 would have given a trivial sequence 1,2,3,4,5....
Every partial concatenation is a left substring of the concatenation of natural numbers.
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EXAMPLE
| a(2) = 34 = 2*17; a(7) = 17181920 = 7*2454560.
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CROSSREFS
| Cf. A077294, A088597, A088598.
Sequence in context: A133294 A082240 A088596 * A053682 A033570 A163661
Adjacent sequences: A077290 A077291 A077292 * A077294 A077295 A077296
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KEYWORD
| base,nonn
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AUTHOR
| Amarnath Murthy (amarnath_murthy(AT)yahoo.com), Nov 03 2002
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EXTENSIONS
| Corrected and extended by Ray Chandler (rayjchandler(AT)sbcglobal.net), Oct 18 2003
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