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 A227181 #26 Jul 03 2025 15:24:47
%S A227181 0,1,2,3,4,3,4,5,6,7,8,9,4,5,6,7,8,9,10,11,12,13,14,15,16,5,6,7,8,9,
%T A227181 10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,6,7,8,9,10,11,12,13,
%U A227181 14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36
%N A227181 Irregular table: integers from n to n^2 followed by integers from (n+1) to (n+1)^2.
%H A227181 Antti Karttunen, <a href="/A227181/b227181.txt">Rows 0..31, flattened</a>
%F A227181 a(n) = A227177(n)+ A227179(n). [As a sequence].
%e A227181 Row n is A002061(n) terms long, and contains successive integers from n to n*n:
%e A227181 0;
%e A227181 1;
%e A227181 2, 3, 4;
%e A227181 3, 4, 5, 6, 7, 8, 9;
%e A227181 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16;
%e A227181 ...
%t A227181 Flatten[(#+Range[(#1-2) (#1-1)+1]-2&)[Range[7]]] (* _Peter J. C. Moses_, Jul 11 2013 *)
%t A227181 Table[Range[n,n^2],{n,0,6}]//Flatten (* _Harvey P. Dale_, Apr 03 2021 *)
%o A227181 (Scheme) (define (A227181 n) (+ (A227177 n) (A227179 n)))
%o A227181 (Python)
%o A227181 from sympy import integer_nthroot
%o A227181 def A227181(n): return n-(r:=(m:=integer_nthroot(k:=3*n,3)[0])-(k<=m*(m**2+2)))*(r**2-1)//3 # _Chai Wah Wu_, Nov 07 2024
%Y A227181 Right edge: A000290. Central diagonal: A000217. Cf. also A227147.
%K A227181 nonn,tabf
%O A227181 0,3
%A A227181 _Antti Karttunen_, Jul 03 2013