This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A270873 #25 Mar 27 2025 21:31:54
%S A270873 21,7668,75545,545730,3015021,13239896,48243393,151298070,420233285,
%T A270873 1056651996,2446142121,5282430218,10751650845,20796493440,38483939921,
%U A270873 68504620446,117836491893,196610583620,319221957945,505734798546,783636668621,1190003472168
%N A270873 a(n) = n^9 + 8*n^8 + 43*n^7 + 159*n^6 + 452*n^5 + 997*n^4 + 1725*n^3 + 2272*n^2 + 1990*n + 21.
%H A270873 Vincenzo Librandi, <a href="/A270873/b270873.txt">Table of n, a(n) for n = 0..1000</a>
%H A270873 Andrew Misseldine, <a href="http://arxiv.org/abs/1508.03757">Counting Schur Rings over Cyclic Groups</a>, arXiv preprint arXiv:1508.03757 [math.RA], 2015. (page 19, 4th row; page 21, 9th row).
%H A270873 <a href="/index/Rec#order_10">Index entries for linear recurrences with constant coefficients</a>, signature (10,-45,120,-210,252,-210,120,-45,10,-1).
%F A270873 G.f.: (21+7458*x-190*x^2+132820*x^3+41496*x^4+187124*x^5-30698*x^6+30660*x^7-6565*x^8+754*x^9)/(1-x)^10.
%F A270873 a(n) = 10*a(n-1) - 45*a(n-2) + 120*a(n-3) - 210*a(n-4) + 252*a(n-5) - 210*a(n-6) + 120*a(n-7) - 45*a(n-8) + 10*a(n-9) - a(n-10).
%t A270873 Table[n^9 + 8 n^8 + 43 n^7 + 159 n^6 + 452 n^5 + 997 n^4 + 1725 n^3 + 2272 n^2 + 1990 n + 21, {n, 0, 40}]
%t A270873 LinearRecurrence[{10,-45,120,-210,252,-210,120,-45,10,-1},{21,7668,75545,545730,3015021,13239896,48243393,151298070,420233285,1056651996},30] (* _Harvey P. Dale_, Dec 02 2018 *)
%o A270873 (Magma) [n^9+8*n^8+43*n^7+159*n^6+452*n^5+997*n^4+1725*n^3+2272*n^2+1990*n+21: n in [0..40]];
%o A270873 (PARI) my(x='x+O('x^99)); Vec((21+7458*x-190*x^2+132820*x^3+41496*x^4+187124*x^5-30698*x^6+30660*x^7-6565*x^8+754*x^9)/(1-x)^10) \\ _Altug Alkan_, Apr 04 2016
%Y A270873 Cf. A270867, A270868, A270869, A270870, A270871, A270872.
%K A270873 nonn,easy
%O A270873 0,1
%A A270873 _Vincenzo Librandi_, Apr 04 2016