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 A197357 #18 Jun 08 2013 12:28:05
%S A197357 1,10,55,670,4840,55252,436975,4816030,40051495,432457640,3715101654,
%T A197357 39581170420,347847754670,3671331273480,32811494188975,
%U A197357 343900019857310,3113537578058979,32458256583753952,296896918816556380,3081918923741896840
%N A197357 Number of n-digits integers for which the sum of the odd-positioned digits equals the sum of the even-positioned digits.
%C A197357 a(n) is the number of n-digit integers such that the sum of the odd-positioned digits is equal to the sum of the even-positioned digits, leading zeros being allowed in the integers.
%H A197357 Colin Barker, <a href="/A197357/b197357.txt">Table of n, a(n) for n = 1..200</a>
%e A197357 The number 28754 is one of the 4840 5-digit numbers because 2+7+4 = 8+5.
%o A197357 (PARI) a(n) = {nb = 0; for (i=0, 10^n-1, digs = digits(i, 10); while(#digs != n, digs = concat(0, digs)); so = 0; forstep(j=1, n, 2, so += digs[j]); se = 0; forstep(j=2, n, 2, se += digs[j]); if (se == so, nb++);); return (nb);} \\ _Michel Marcus_, Jun 08 2013
%Y A197357 This sequence has some numbers in common with both A025015 and A174061. In fact, A174061 consists of the elements a(2n), and the elements a(2n) are all elements of A025015.
%K A197357 nonn,base
%O A197357 1,2
%A A197357 _Colin Barker_, Oct 13 2011