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 A045801 #30 Jul 09 2025 03:51:00
%S A045801 11,39,73,77,111,139,173,177,211,239,273,277,311,339,373,377,411,439,
%T A045801 473,477,511,539,573,577,611,639,673,677,711,739,773,777,811,839,873,
%U A045801 877,911,939,973,977,1011,1039,1073,1077,1111,1139,1173,1177,1211,1239
%N A045801 1-ish numbers (end in 11, 39, 73, 77).
%H A045801 Reinhard Zumkeller, <a href="/A045801/b045801.txt">Table of n, a(n) for n = 1..1000</a>
%H A045801 <a href="/index/Rec#order_05">Index entries for linear recurrences with constant coefficients</a>, signature (1,0,0,1,-1).
%F A045801 G.f.: x*(11+28*x+34*x^2+4*x^3+23*x^4)/(1-x-x^4+x^5). - _Colin Barker_, Jan 23 2012
%F A045801 a(n) = (50*n-12*i^(n*(n-1))-9*(-1)^n-25)/2, where i=sqrt(-1). - _Bruno Berselli_, Feb 23 2012
%t A045801 Table[100n+k,{n,0,20},{k,{11,39,73,77}}]//Flatten (* or *) LinearRecurrence[ {1,0,0,1,-1},{11,39,73,77,111},80] (* _Harvey P. Dale_, Jul 05 2019 *)
%o A045801 (Haskell)
%o A045801 import Data.List (findIndices)
%o A045801 a045801 n = a045801_list !! (n-1)
%o A045801 a045801_list = findIndices (`elem` [11,39,73,77]) $ cycle [0..99]
%o A045801 -- _Reinhard Zumkeller_, Jan 23 2012
%Y A045801 Cf. A045800-A045809, A045572, A045797, A045798.
%K A045801 nonn,base,easy
%O A045801 1,1
%A A045801 _J. H. Conway_
%E A045801 More terms from _Erich Friedman_.