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 A109497 #8 Feb 16 2025 08:32:58 %S A109497 1,1,2,2,2,2,3,3,4,4,4,4,5,5,6,6,6,6,6,6,7,7,7,7,8,8,8,8,8,8,9,9,10, %T A109497 10,10,10,11,11,11,11,11,11,12,12,12,12,12,12,13,13,14,14,14,14,14,14, %U A109497 14,14,14,14,14,14,15,15,15,15,16,16,17,17,17,17,18,18,19,19,19,19,20,20 %N A109497 Number of lucky numbers <= n. %D A109497 R. K. Guy, Unsolved Problems in Number Theory, C3. %H A109497 V. Gardiner, R. Lazarus, N. Metropolis, and S. Ulam, <a href="https://www.jstor.org/stable/3029719">On certain sequences of integers defined by sieves</a>, Mathematics Magazine, 29(3) (1955), 117-122. %H A109497 Martin Gardner, <a href="http://dx.doi.org/10.1007/BF03024427">Lucky numbers and 2187</a>, Math. Intellig., 19(2) (1997), 26-29. %H A109497 I. Peterson, MathTrek, <a href="http://www.sciencenews.org/pages/sn_arc97/9_6_97/mathland.htm">Martin Gardner's Lucky Numbers</a> %H A109497 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/LuckyNumber.html">Lucky Number</a> %H A109497 Wikipedia, <a href="http://en.wikipedia.org/wiki/Lucky_number">Lucky Number</a> %e A109497 a(9)=4 because there are 4 lucky numbers less than or equal to 9 (1, 3, 7, 9) %Y A109497 Cf. A000959. %Y A109497 Partial sums of A145649. %K A109497 nonn %O A109497 0,3 %A A109497 Shawn M. Moore (sartak(AT)gmail.com), Jun 30 2005