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A053067
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a(n) is the concatenation of next n numbers (omit leading 0's).
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31
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1, 23, 456, 78910, 1112131415, 161718192021, 22232425262728, 2930313233343536, 373839404142434445, 46474849505152535455, 5657585960616263646566, 676869707172737475767778, 79808182838485868788899091, 9293949596979899100101102103104105, 106107108109110111112113114115116117118119120
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OFFSET
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1,2
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COMMENTS
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The second term is a prime. When is the next prime, if there is another? - N. J. A. Sloane, Dec 16 2016
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REFERENCES
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Felice Russo, A set of new Smarandache functions, sequences and conjectures in number theory, American Research Press 2000.
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LINKS
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MATHEMATICA
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Table[FromDigits[Flatten[IntegerDigits/@Range[(n(n-1))/2+1, (n(n+1))/2]]], {n, 20}] (* Harvey P. Dale, Jan 23 2016 *)
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PROG
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(PARI) a(n) = my(s = ""); for (i=n*(n-1)/2 + 1, n*(n+1)/2, s = concat(s, Str(i)); ); eval(s); \\ Michel Marcus, Aug 11 2017
(Python)
def a(n): return int("".join(map(str, range((n-1)*n//2+1, n*(n+1)//2+1))))
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CROSSREFS
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KEYWORD
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easy,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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