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 A241494 #24 Apr 24 2025 22:28:19
%S A241494 0,1,2,3,4,5,6,7,8,9,1,0,1,2,3,4,5,6,7,8,2,1,0,1,2,3,4,5,6,7,3,2,1,0,
%T A241494 1,2,3,4,5,6,4,3,2,1,0,1,2,3,4,5,5,4,3,2,1,0,1,2,3,4,6,5,4,3,2,1,0,1,
%U A241494 2,3,7,6,5,4,3,2,1,0,1,2,8,7,6,5
%N A241494 Pyramid Top Numbers: write the decimal digits of 'n' (a nonnegative integer) and take successive absolute differences ("pyramidalization"). The number at the top of the pyramid is 'a(n)'.
%C A241494 Through the so-called "pyramidalization" process (see A227876), a given nonnegative integer is expanded into its digits and transformed into a pyramid of successive absolute differences between digits. The present sequence is built only with the top number 'a(n)' generated from its correspondent nonnegative integer 'n'.
%H A241494 Filipi R. de Oliveira, <a href="/A241494/b241494.txt">Table of n, a(n) for n = 0..9999</a>
%F A241494 a(n)=n, if 0<=n<=9.
%F A241494 a(n)=|mod(n;10)-floor(n/10)|, if 10<=n<=99.
%e A241494 If n=1735, a(n)=0:
%e A241494 ______0 ------>a(n)
%e A241494 ____2_:_2
%e A241494 __6_:_4_:_2
%e A241494 1_:_7_:_3_:_5
%o A241494 (PARI) a(n)=my(d=Vecsmall(digits(n))); forstep(k=#d-1,1,-1, for(j=1,k, d[j]=abs(d[j]-d[j+1]))); d[1] \\ _Charles R Greathouse IV_, Apr 24 2025
%Y A241494 Cf. A227876 for the pyramidalization process.
%Y A241494 Cf. A076313 - its first 100 terms have the same absolute value, diverging afterwards; cf. A225693 and A055017 (A040997) for the same reason.
%K A241494 base,nonn,easy,look
%O A241494 0,3
%A A241494 _Filipi R. de Oliveira_, Apr 24 2014