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A077695
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a(n) = triangular number pertaining to the number f(n) obtained by concatenating n n times.
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1
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1, 253, 55611, 9876790, 1543206790, 222222111111, 30246911419753, 3950617249382716, 499999999500000000, 51015202530354045509590858075706560555, 617283950617283950617716049382716049382716
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OFFSET
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1,2
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COMMENTS
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a(n) = triangular number corresponding to A000461(n).
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LINKS
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EXAMPLE
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a(4) = 9876790 = 4444*4445/2.
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MATHEMATICA
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(#(#+1))/2&/@Table[FromDigits[Flatten[IntegerDigits/@PadRight[{}, n, n]]], {n, 15}] (* Harvey P. Dale, Oct 15 2021 *)
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CROSSREFS
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KEYWORD
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base,nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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