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A062123
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a(n) = (9n^2 + 9n + 4)/2.
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10
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2, 11, 29, 56, 92, 137, 191, 254, 326, 407, 497, 596, 704, 821, 947, 1082, 1226, 1379, 1541, 1712, 1892, 2081, 2279, 2486, 2702, 2927, 3161, 3404, 3656, 3917, 4187, 4466, 4754, 5051, 5357, 5672, 5996, 6329, 6671, 7022, 7382, 7751, 8129, 8516, 8912, 9317
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refs;
listen;
history;
text;
internal format)
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OFFSET
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0,1
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COMMENTS
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REFERENCES
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I. P. Goulden and D. M. Jackson, Combinatorial Enumeration, Wiley, N.Y., 1983,(2.3.14).
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LINKS
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FORMULA
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G.f.: (1+2*x)*(2+x)/(1-x)^3. Generally, g.f. for k-th column of A046741 is coefficient of y^k in expansion of (1-y)/((1-y-y^2)*(1-y)-(1+y)*x).
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MATHEMATICA
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Table[2 +9*n*(1+n)/2, {n, 0, 50}] (* G. C. Greubel, Jan 31 2019 *)
LinearRecurrence[{3, -3, 1}, {2, 11, 29}, 50] (* Harvey P. Dale, Jan 12 2020 *)
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PROG
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(PARI) for (n=0, 1000, write("b062123.txt", n, " ", 2 + (n + n^2)*9/2) ) \\ Harry J. Smith, Aug 02 2009
(Magma) [2 +9*n*(1+n)/2: n in [0..50]]; // G. C. Greubel, Jan 31 2019
(Sage) [2 +9*n*(1+n)/2 for n in range(50)] # G. C. Greubel, Jan 31 2019
(GAP) List([0..50], n -> 2 +9*n*(1+n)/2); # G. C. Greubel, Jan 31 2019
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CROSSREFS
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KEYWORD
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nonn,easy
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AUTHOR
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EXTENSIONS
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More terms from Larry Reeves (larryr(AT)acm.org), Jun 06 2001
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STATUS
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approved
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