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 A088405 #11 Dec 11 2024 12:22:54 %S A088405 1,4,7,10,34,37,40,67,70,100,334,337,340,367,370,400,667,670,700,1000, %T A088405 3334,3337,3340,3367,3370,3400,3667,3670,3700,4000,6667,6670,6700, %U A088405 7000,10000,33334,33337,33340,33367,33370,33400,33667,33670,33700,34000 %N A088405 a(n) = A052217(n)/3. %H A088405 Alois P. Heinz, <a href="/A088405/b088405.txt">Table of n, a(n) for n = 1..10000</a> %o A088405 (Python) %o A088405 from math import comb, isqrt %o A088405 from sympy import integer_nthroot %o A088405 def A088405(n): return (10**((m:=integer_nthroot(6*n,3)[0])-(a:=n<=comb(m+2,3)))+10**((k:=isqrt(b:=(c:=n-comb(m-a+2,3))<<1))-((b<<2)<=(k<<2)*(k+1)+1))+10**(c-1-comb(k+(b>k*(k+1)),2)))//3 # _Chai Wah Wu_, Dec 11 2024 %Y A088405 Cf. A052217. %K A088405 nonn %O A088405 1,2 %A A088405 _Ray Chandler_, Sep 29 2003