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Search: id:A114696
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| A114696 |
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Expansion of (1+4*x+x^2)/((x-1)*(x+1)*(x^2+2*x-1)); a Pellian-related sequence. |
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+0
4
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| 1, 6, 15, 40, 97, 238, 575, 1392, 3361, 8118, 19599, 47320, 114241, 275806, 665855, 1607520, 3880897, 9369318, 22619535, 54608392, 131836321, 318281038, 768398399, 1855077840, 4478554081
(list; graph; listen)
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OFFSET
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0,2
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COMMENT
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Elements of odd index give match to A065113: Sum of the squares of the n-th and the n+1_st triangular numbers (A000217) is a perfect square. Generating floretion: - 1.5'i + 'j + 'k - .5i' + j' + k' + .5'ii' - .5'jj' - .5'kk' - 'ij' + 'ik' - 'ji' + .5'jk' + 2'ki' - .5'kj' + .5e
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CROSSREFS
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Cf. A100828, A111954, A113224, A114647, A114688, A114689, A114695, A114697, A000129, A005409.
Sequence in context: A128443 A135854 A083011 this_sequence A106368 A100491 A117961
Adjacent sequences: A114693 A114694 A114695 this_sequence A114697 A114698 A114699
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KEYWORD
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easy,nonn
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AUTHOR
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Creighton Dement (creighton.k.dement(AT)uni-oldenburg.de), Feb 18 2006
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