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Search: id:A091018
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| A091018 |
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Numbers in n-th upward diagonal of triangle T : 0; 1, 2; 3, 4, 5; 6, 7, 8, 9; ... |
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+0
3
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| 0, 1, 3, 2, 6, 4, 10, 7, 5, 15, 11, 8, 21, 16, 12, 9, 28, 22, 17, 13, 36, 29, 23, 18, 14, 45, 37, 30, 24, 19, 55, 46, 38, 31, 25, 20, 66, 56, 47, 39, 32, 26, 78, 67, 57, 48, 40, 33, 27, 91, 79, 68, 58, 49, 41, 34, 105, 92, 80, 69, 59, 50, 42, 35, 120, 106, 93, 81, 70, 60, 51
(list; graph; listen)
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OFFSET
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0,3
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COMMENT
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See also A090894 (downward diagonal).
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FORMULA
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a(n) = A056536(n+1) - 1.
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EXAMPLE
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0; 1; 3,2; 6,4; 10,7,5; 15,11,8; 21,16,12,9; 28,22,17,13; ...
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PROGRAM
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(PARI) T(n, k)=(n-k)^2+(n+k) /* Michael Somos May 31 2005 */
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CROSSREFS
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Sequence in context: A006368 A105354 A094077 this_sequence A113320 A092401 A116626
Adjacent sequences: A091015 A091016 A091017 this_sequence A091019 A091020 A091021
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KEYWORD
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easy,nonn
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AUTHOR
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DELEHAM Philippe (kolotoko(AT)wanadoo.fr), Feb 25 2004
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