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A081352
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Main diagonal of square maze arrangement of natural numbers A081349.
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7
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1, 7, 11, 21, 29, 43, 55, 73, 89, 111, 131, 157, 181, 211, 239, 273, 305, 343, 379, 421, 461, 507, 551, 601, 649, 703, 755, 813, 869, 931, 991, 1057, 1121, 1191, 1259, 1333, 1405, 1483, 1559, 1641, 1721, 1807, 1891, 1981, 2069, 2163, 2255, 2353, 2449, 2551
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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LINKS
| B. Berselli, Table of n, a(n) for n = 0..10000 [From Bruno Berselli (berselli.bruno(AT)yahoo.it), Aug 01 2010]
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FORMULA
| a(n)=(n + 1)(n + 2) - (-1)^n=2C(n+2, 2)-(-1)^n.
Contribution from Bruno Berselli (berselli.bruno(AT)yahoo.it), Aug 01 2010: (Start)
G.f.: (1+5*x-3*x^2+x^3)/((1+x)*(1-x)^3).
a(n)-2*a(n-1)+2*a(n-3)-a(n-4) = 0 with n>3. (End)
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CROSSREFS
| Cf. A081350, A081351, A054569.
Sequence in context: A076854 A194828 A035704 * A190673 A175651 A039511
Adjacent sequences: A081349 A081350 A081351 * A081353 A081354 A081355
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KEYWORD
| easy,nonn
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AUTHOR
| Paul Barry (pbarry(AT)wit.ie), Mar 19 2003
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