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 A078891 Concatenate first n triangular numbers in reverse order. 1
 1, 31, 631, 10631, 1510631, 211510631, 28211510631, 3628211510631, 453628211510631, 55453628211510631, 6655453628211510631, 786655453628211510631, 91786655453628211510631, 10591786655453628211510631, 12010591786655453628211510631 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 REFERENCES Shyam Sunder Gupta, Smarandache Sequence of Triangular Numbers, Smarandache Notions Journal, (to appear in Vol. 14, 2003). LINKS EXAMPLE a(3)=631 because 6,3,1 are first 3 triangular numbers in reverse order. MAPLE a:= proc(n) a(n):= `if`(n=1, 1, parse(cat(n*(n+1)/2, a(n-1)))) end: seq(a(n), n=1..20);  # Alois P. Heinz, Jan 13 2021 MATHEMATICA Table[FromDigits[Flatten[IntegerDigits[Table[n*(n+1)/2, {n, m, 1, -1}]]]], {m, 1, 20}] CROSSREFS Cf. A000217. Sequence in context: A028013 A028073 A089758 * A078914 A068147 A025009 Adjacent sequences:  A078888 A078889 A078890 * A078892 A078893 A078894 KEYWORD base,easy,nonn,less AUTHOR Shyam Sunder Gupta, Jan 10 2003 STATUS approved

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Last modified June 28 21:04 EDT 2022. Contains 354907 sequences. (Running on oeis4.)