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A124093
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Triangular numbers alternating with squares.
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1
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0, 0, 1, 1, 3, 4, 6, 9, 10, 16, 15, 25, 21, 36, 28, 49, 36, 64, 45, 81, 55, 100, 66, 121, 78, 144, 91, 169, 105, 196, 120, 225, 136, 256, 153, 289, 171, 324, 190, 361, 210, 400, 231, 441, 253, 484, 276, 529, 300, 576, 325, 625, 351, 676, 378, 729, 406, 784, 435, 841
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,5
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FORMULA
| a(n)=n(n+2)/8 if n is even; a(n)=(n-1)^2/4 if n is odd (n>=0). - Emeric Deutsch (deutsch(AT)duke.poly.edu), Nov 29 2006
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MAPLE
| a:=proc(n) if n mod 2 = 0 then n*(n+2)/8 else (n-1)^2/4 fi end: seq(a(n), n=0..70); - Emeric Deutsch (deutsch(AT)duke.poly.edu), Nov 29 2006
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MATHEMATICA
| tr=Table[{k(k+1)/2, k^2}, {k, 0, 100}]//Flatten (Seidov)
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CROSSREFS
| Cf. A123596.
Sequence in context: A034706 A054686 A005214 * A025061 A037969 A153236
Adjacent sequences: A124090 A124091 A124092 * A124094 A124095 A124096
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KEYWORD
| nonn
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com), based on a suggestion from Robert G. Wilson v, Nov 27 2006
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EXTENSIONS
| More terms from Zak Seidov, Nov 28 2006
More terms from Emeric Deutsch (deutsch(AT)duke.poly.edu), Nov 29 2006
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