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A007401
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Add n-1 to n-th term of `n appears n times' sequence (A002024).
(Formerly M2316)
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4
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1, 3, 4, 6, 7, 8, 10, 11, 12, 13, 15, 16, 17, 18, 19, 21, 22, 23, 24, 25, 26, 28, 29, 30, 31, 32, 33, 34, 36, 37, 38, 39, 40, 41, 42, 43, 45, 46, 47, 48, 49, 50, 51, 52, 53, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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COMMENTS
| Complement of A000096 = increasing sequence of positive integers excluding n*(n+3)/2. - Jonathan Vos Post (jvospost3(AT)gmail.com), Aug 13 2005
As a triangle: (1; 3,4; 6,7,8; 10,11,12,13;...), Row sums = A127736: (1, 7, 21, 46, 85, 141, 217,...) - Gary W. Adamson (qntmpkt(AT)yahoo.com), Oct 25 2007
Odd primes are a subsequence except 5, cf. A004139. [Reinhard Zumkeller, Jul 18 2011]
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REFERENCES
| N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
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LINKS
| Reinhard Zumkeller, Table of n, a(n) for n = 1..10000
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MATHEMATICA
| f[n_] := n + Floor[ Sqrt[2n] - 1/2]; Array[f, 66]; (* Robert G. Wilson v, Feb 13 2011 *)
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PROG
| (PARI) a(n)=n+floor(sqrt(n+n)-1/2) \\ Charles R Greathouse IV, Feb 13 2011
(PARI) for(m=1, 9, for(n=m*(m+1)/2, (m^2+3*m-2)/2, print1(n", "))) \\ Charles R Greathouse IV, Feb 13 2011
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CROSSREFS
| Cf. A002024, A000096, A127736.
Sequence in context: A179872 A075747 A143344 * A042954 A062975 A047299
Adjacent sequences: A007398 A007399 A007400 * A007402 A007403 A007404
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KEYWORD
| nonn,easy
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com), Mira Bernstein
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