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A076069
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Largest number formed as concatenation of a permutation of the n consecutive numbers 1+n(n-1)/2, ..., n(n+1)/2 (written in decimal).
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1
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1, 32, 654, 98710, 1514131211, 212019181716, 28272625242322, 3635343332313029, 454443424140393837, 55545352515049484746, 6665646362616059585756, 787776757473727170696867, 91908988878685848382818079, 9998979695949392105104103102101100
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OFFSET
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1,2
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COMMENTS
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Nontrivial (i.e., different from concatenation in reverse order) whenever a number of the form 10^k is in the considered range of n numbers; then a(n) is given as concatenation (10^k-1)...(1+n(n-1)/2)(n(n+1)/2)...(10^k).
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LINKS
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EXAMPLE
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1, then a concatenation of a permutation of 2 and 3, then a concatenation of a permutation of 4, 5 and 6.
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PROG
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(PARI 2.4.2) a(n)=eval(concat(vecsort(vector(n, i, Str(i+n*(n-1)/2)), , 4)))
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CROSSREFS
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KEYWORD
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nonn,easy,less,base
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AUTHOR
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EXTENSIONS
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Definition modified to obtain a new sequence different from (earlier duplicate) A080480. M. F. Hasler, Jun 29 2011.
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STATUS
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approved
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