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 A063009 #22 Dec 06 2024 20:19:00 %S A063009 0,1,100,121,10000,10201,12100,12321,1000000,1002001,1020100,1022121, %T A063009 1210000,1212201,1232100,1234321,100000000,100020001,100200100, %U A063009 100220121,102010000,102030201,102212100,102232321,121000000,121022001 %N A063009 Write n in binary then square as if written in base 10. %C A063009 The original description was: "Pre-carry binary squares: write n in binary then square as if written in a base large enough to avoid carries". But I changed it, since I prefer to work in base 10. There is no difference until a(1023). - _N. J. A. Sloane_, May 21 2002 %H A063009 Harry J. Smith, <a href="/A063009/b063009.txt">Table of n, a(n) for n=0,...,1000</a> %H A063009 David Applegate, Marc LeBrun and N. J. A. Sloane, <a href="http://neilsloane.com/doc/carry1.pdf">Carryless Arithmetic (I): The Mod 10 Version</a>. %F A063009 a(2n) = 100*a(n); a(2n+1) = 100*a(n) + 20*A007088(n) + 1. %e A063009 a(11)=1022121 since 11 written in binary is 1011 and 1011^2 = 1011000 + 0 + 10110 + 1011 = 1022121. %e A063009 a(1023) = 1111111111^2 = 1234567900987654321. %o A063009 (PARI) a(n) = fromdigits(binary(n))^2; \\ _Ruud H.G. van Tol_, Dec 08 2022 %Y A063009 Cf. A007088 for binary numbers, A001737 for binary squares (post-carry), A063010 for carryless binary squares. %K A063009 base,easy,nonn %O A063009 0,3 %A A063009 _Henry Bottomley_, Jul 04 2001