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A080456
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a(1) = a(2) = 2; for n>2, a(n) = a(n-1) if n is already in the sequence, a(n) = a(n-1)+4 otherwise.
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1
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2, 6, 10, 14, 18, 18, 22, 26, 30, 30, 34, 38, 42, 42, 46, 50, 54, 54, 58, 62, 66, 66, 70, 74, 78, 78, 82, 86, 90, 90, 94, 98, 102, 102, 106, 110, 114, 114, 118, 122, 126, 126, 130, 134, 138, 138, 142, 146, 150, 150, 154, 158, 162, 162, 166, 170, 174, 174
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OFFSET
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1,1
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COMMENTS
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First differences are 4-periodic.
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LINKS
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Table of n, a(n) for n=1..58.
B. Cloitre, N. J. A. Sloane and M. J. Vandermast, Numerical analogues of Aronson's sequence, J. Integer Seqs., Vol. 6 (2003), #03.2.2.
B. Cloitre, N. J. A. Sloane and M. J. Vandermast, Numerical analogues of Aronson's sequence (math.NT/0305308)
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FORMULA
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a(n)=-2+4*((n+2) mod (n+1))+Sum_{k=0..n}{(1/2)*[(k mod 4)+((k+1) mod 4)-((k+2) mod 4)+3*((k+3) mod 4)]} - Paolo P. Lava, Aug 29 2007
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CROSSREFS
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Cf. A080455-A080458, A080036, A080037.
Sequence in context: A191256 A191259 A184914 * A187884 A068977 A111284
Adjacent sequences: A080453 A080454 A080455 * A080457 A080458 A080459
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KEYWORD
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nonn
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AUTHOR
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N. J. A. Sloane, Mar 20 2003
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STATUS
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approved
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