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 A081346 First column in maze arrangement of natural numbers A081344. 3
 1, 2, 9, 10, 25, 26, 49, 50, 81, 82, 121, 122, 169, 170, 225, 226, 289, 290, 361, 362, 441, 442, 529, 530, 625, 626, 729, 730, 841, 842, 961, 962, 1089, 1090, 1225, 1226, 1369, 1370, 1521, 1522, 1681, 1682, 1849, 1850, 2025, 2026, 2209, 2210, 2401, 2402, 2601 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS Interleaves odd squares A016754 with central polygonal numbers A001844. LINKS Vincenzo Librandi, Table of n, a(n) for n = 0..10000 Index entries for linear recurrences with constant coefficients, signature (1,2,-2,-1,1). FORMULA a(n) = n^2 + n + 1 + n*(-1)^n. a(2*n) = A016754(n), a(2*n+1) = 2*A001844(n). G.f.: (1 + x + 5*x^2 - x^3 + 2*x^4)/((1-x)^3*(1+x)^2). [Colin Barker, Sep 03 2012] PROG (MAGMA) [n^2+n+1+n*(-1)^n: n in [0..50]]; // Vincenzo Librandi, Sep 05 2011 CROSSREFS Cf. A081345. Sequence in context: A005695 A079747 A191576 * A301872 A290592 A058551 Adjacent sequences:  A081343 A081344 A081345 * A081347 A081348 A081349 KEYWORD easy,nonn AUTHOR Paul Barry, Mar 19 2003 STATUS approved

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Last modified October 14 03:58 EDT 2019. Contains 327995 sequences. (Running on oeis4.)