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 A062203 #6 May 10 2013 12:44:47 %S A062203 1,1,1,3,4,7,14,21,38,65,110,195,329,564,975,1675,2885,4950,8503, %T A062203 14627,25158,43255,74325,127775,219662,377662,649313,1116085,1918690, %U A062203 3298498,5670521,9748641,16758575,28809772,49527786,85143986,146373609 %N A062203 Number of compositions of n such that two adjacent parts are not equal modulo 5. %D A062203 I. P. Goulden and D. M. Jackson, Combinatorial Enumeration, Wiley, N.Y., 1983, (Problem 2.4.13). %F A062203 G.f.: -(x^5-x-1)*(x^5-x^2-1)*(x^5-x^3-1)*(x^5-x^4-1) / (x^25 -x^24-x^23 -3*x^20+3*x^19 +3*x^18+x^17 +x^16+9*x^15 -5*x^14-5*x^13 -5*x^12-5*x^11 -9*x^10+2*x^9 +2*x^8+4*x^7 +4*x^6+7*x^5 +x^4+x^3-1). Generally, g.f. for the number of compositions of n such that two adjacent parts are not equal modulo p is 1/(1-Sum_{i=1..p} x^i/(1+x^i-x^p)). %Y A062203 Cf. A003242, A062200-A062202. %K A062203 nonn %O A062203 0,4 %A A062203 _Vladeta Jovovic_, Jun 13 2001