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 A048937 #21 Mar 14 2025 19:18:10
%S A048937 13078260,107650322640,113024597400,119634515208,134549287600,
%T A048937 135173486250,138130447950,146083269717,150967233648,216315684000,
%U A048937 221089445500,315987404670,463997983680,472812953760,10174695862032,10178463985200,10185571893960,10476754939728,10624657891320
%N A048937 Numbers n with an even number of digits, n = d_1 d_2 ... d_n, such that there are exactly three ways to partition the digits into two groups of size n/2, say f_1 ... f_{n/2} and g_1 ... g_{n/2}, such that n = f_1 ... f_{n/2} * g_1 ... g_{n/2}.
%C A048937 f_{n/2} and g_{n/2} may not both be zero.
%C A048937 Vampire numbers (definition 2) having exactly three distinct pairs of fangs.
%D A048937 C. A. Pickover, "Vampire Numbers." Ch. 30 in Keys to Infinity. New York: Wiley, pp. 227-231, 1995.
%H A048937 Shyam Sunder Gupta, <a href="https://doi.org/10.1007/978-981-97-2465-9_20">Cab and Vampire Numbers</a>, Exploring the Beauty of Fascinating Numbers, Springer (2025) Ch. 20, 499-512.
%H A048937 Walter Schneider, <a href="http://web.archive.org/web/2004/www.wschnei.de/digit-related-numbers/vampire.html">Vampire numbers</a>
%H A048937 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/VampireNumber.html">Vampire Number.</a>
%e A048937 13078260 = 1620*8073 = 1863*7020 = 2070*6318; 107650322640 = 153204*702660 = 140532*766020 = 200760*536214.
%Y A048937 Cf. A014575, A048933, ..., A048939.
%K A048937 nonn,base
%O A048937 1,1
%A A048937 _Eric W. Weisstein_
%E A048937 More terms found by Walter Schneider, Feb 11 2002 and communicated by _Hans Havermann_, Oct 10 2002
%E A048937 More terms from _Jens Kruse Andersen_, Dec 01 2002