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1, 6, 9, 18, 25, 38, 49, 66, 81, 102, 121, 146, 169, 198, 225, 258, 289, 326, 361, 402, 441, 486, 529, 578, 625, 678, 729, 786, 841, 902, 961, 1026, 1089, 1158, 1225, 1298, 1369, 1446, 1521, 1602, 1681, 1766, 1849, 1938, 2025, 2118, 2209, 2306, 2401, 2502
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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LINKS
| Vincenzo Librandi, Table of n, a(n) for n = 0..10000
Index to sequences with linear recurrences with constant coefficients, signature (2,0,-2,1).
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FORMULA
| G.f.: (1+4*x-3*x^2+2*x^3)/((1+x)*(1-x)^3).
a(2*n) = (2*n+1)^2 = A016754(n), a(2*n+1) = 4*n^2+8*n+6 = A005899(n+1).
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PROG
| (MAGMA) [n^2+2*n+2-(-1)^n: n in [0..50]]; // Vincenzo Librandi, Sep 06 2011
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CROSSREFS
| Cf. A080335.
Sequence in context: A020183 A039280 A045091 * A078415 A023041 A118277
Adjacent sequences: A086952 A086953 A086954 * A086956 A086957 A086958
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KEYWORD
| nonn,easy
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AUTHOR
| Paul Barry (pbarry(AT)wit.ie), Jul 25 2003
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