cp's OEIS Frontend

A060354 The n-th n-gonal number: a(n) = n*(n^2 - 3*n + 4)/2.

%I A060354 #86 May 12 2025 18:04:01
%S A060354 0,1,2,6,16,35,66,112,176,261,370,506,672,871,1106,1380,1696,2057,
%T A060354 2466,2926,3440,4011,4642,5336,6096,6925,7826,8802,9856,10991,12210,
%U A060354 13516,14912,16401,17986,19670,21456,23347,25346,27456,29680,32021
%N A060354 The n-th n-gonal number: a(n) = n*(n^2 - 3*n + 4)/2.
%C A060354 Binomial transform of (0,1,0,3,0,0,0,...). - _Paul Barry_, Sep 14 2006
%C A060354 Also the number of permutations of length n which can be sorted by a single cut-and-paste move (in the sense of Cranston, Sudborough, and West). - _Vincent Vatter_, Aug 21 2013
%C A060354 Main diagonal of A317302. - _Omar E. Pol_, Aug 11 2018
%C A060354 a(n) is the number of ternary strings of length n that contain exactly one 1, zero or two 2's and have no restriction on the number of 0's. For example, a(5) = 35 since the strings are 12200 (30 of this type) and 10000 (5 of this type). - _Enrique Navarrete_, May 08 2025
%H A060354 Harry J. Smith, <a href="/A060354/b060354.txt">Table of n, a(n) for n = 0..1000</a>
%H A060354 D. W. Cranston, I. H. Sudborough, and D. B. West, <a href="http://dx.doi.org/10.1016/j.disc.2007.01.011">Short proofs for cut-and-paste sorting of permutations</a>, Discrete Math. 307, 22 (2007), 2866-2870.
%H A060354 Cheyne Homberger, <a href="http://arxiv.org/abs/1410.2657">Patterns in Permutations and Involutions: A Structural and Enumerative Approach</a>, arXiv preprint 1410.2657 [math.CO], 2014.
%H A060354 C. Homberger and V. Vatter, <a href="http://www.math.ufl.edu/~vatter/publications/poly-classes/">On the effective and automatic enumeration of polynomial permutation classes</a>. [Broken link]
%H A060354 C. Homberger and V. Vatter, <a href="http://arxiv.org/abs/1308.4946">On the effective and automatic enumeration of polynomial permutation classes</a>, arXiv preprint arXiv:1308.4946 [math.CO], 2013-2015.
%H A060354 <a href="/index/Pol#polygonal_numbers">Index to sequences related to polygonal numbers</a>
%H A060354 <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (4,-6,4,-1).
%F A060354 a(n) = (n*(n-2)^2 + n^2)/2.
%F A060354 E.g.f.: exp(x)*x*(1+x^2/2). - _Paul Barry_, Sep 14 2006
%F A060354 G.f.: x*(1-2*x+4*x^2)/(1-x)^4. - _R. J. Mathar_, Sep 02 2008
%F A060354 a(n) = A057145(n,n). - _R. J. Mathar_, Jul 28 2016
%F A060354 a(n) = A000124(n-2) * n. - _Bruce J. Nicholson_, Jul 13 2018
%F A060354 a(n) = Sum_{i=0..n-1} (i*(n-2) + 1). - _Ivan N. Ianakiev_, Sep 25 2020
%p A060354 A060354 := proc(n)
%p A060354     (n*(n-2)^2+n^2)/2 ;
%p A060354 end proc: # _R. J. Mathar_, Jul 28 2016
%t A060354 Table[(n (n-2)^2+n^2)/2,{n,0,50}] (* _Harvey P. Dale_, Aug 05 2011 *)
%t A060354 CoefficientList[Series[x (1 - 2 x + 4 x^2) / (1 - x)^4, {x, 0, 50}], x] (* _Vincenzo Librandi_, Feb 16 2015 *)
%t A060354 Table[PolygonalNumber[n,n],{n,0,50}] (* _Harvey P. Dale_, Mar 07 2016 *)
%t A060354 LinearRecurrence[{4,-6,4,-1},{0,1,2,6},50] (* _Harvey P. Dale_, Mar 07 2016 *)
%o A060354 (PARI) a(n) = { (n*(n - 2)^2 + n^2)/2 } \\ _Harry J. Smith_, Jul 04 2009
%o A060354 (Magma) [(n*(n-2)^2+n^2)/2: n in [0..50]]; // _Vincenzo Librandi_, Feb 16 2015
%Y A060354 First differences of A004255.
%Y A060354 Cf. A000124, A100177, A057145.
%K A060354 easy,nice,nonn
%O A060354 0,3
%A A060354 Hareendra Yalamanchili (hyalaman(AT)mit.edu), Apr 01 2001