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A078891
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Concatenate first n triangular numbers in reverse order.
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1
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1, 31, 631, 10631, 1510631, 211510631, 28211510631, 3628211510631, 453628211510631, 55453628211510631, 6655453628211510631, 786655453628211510631, 91786655453628211510631
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OFFSET
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1,2
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REFERENCES
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Shyam Sunder Gupta, Smarandache Sequence of Triangular Numbers, Smarandache Notions Journal, (to appear in Vol. 14, 2003).
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LINKS
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Table of n, a(n) for n=1..13.
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EXAMPLE
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a(3)=631 because 6,3,1 are first 3 triangular numbers in reverse order.
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MATHEMATICA
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Table[FromDigits[Flatten[IntegerDigits[Table[n*(n+1)/2, {n, m, 1, -1}]]]], {m, 1, 20}]
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CROSSREFS
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Sequence in context: A028013 A028073 A089758 * A078914 A068147 A025009
Adjacent sequences: A078888 A078889 A078890 * A078892 A078893 A078894
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KEYWORD
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base,easy,nonn,less
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AUTHOR
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Shyam Sunder Gupta (guptass(AT)rediffmail.com), Jan 10 2003
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STATUS
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approved
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