Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).
%I #9 Sep 09 2017 23:24:31
%S 0,1,2,3,4,5,6,7,8,9,101,110,121,132,143,154,165,176,187,198,202,211,
%T 220,231,242,253,264,275,286,297,303,312,321,330,341,352,363,374,385,
%U 396,404,413,422,431,440,451,462,473,484,495,505,514,523,532,541,550,561,572,583,594,606,615
%N Concatenated digits of pyramidalized numbers: Write the decimal digits of n (a nonnegative integer) and take successive absolute differences ("pyramidalization"), then concatenate, from left to right, all the digits in each level of the pyramid, and finally concatenate those results for all levels, from the base up. The result is a(n).
%C Through the so-called "pyramidalization" process a given nonnegative integer is decomposed into its digits, which are "reassembled" afterwards by concatenating each level of the pyramid (separately, from left to right) and subsequently concatenating these results, from the base to the top.
%C The number of digits of the resulting number is the triangular number t(d) where d is the number of digits in the original number n.
%H Filipi R. de Oliveira, <a href="/A240237/b240237.txt">Table of n, a(n) for n = 0..9999</a>
%F a(n) = n for 0 <= n <= 9;
%F a(n) = 10*n + |floor(n/10) - (n mod 10)| for 10 <= n <= 99.
%e a(1248) = 1248124121:
%e 1 --> 1
%e 1 2 --> 1.2
%e 1 2 4 --> 1.2.4
%e 1 2 4 8 --> 1.2.4.8 -->> 1248.124.12.1 --> 1248124121
%Y Cf. A227876, which describes the pyramidalization process, and A000217 (triangular numbers). Cf. also A007908.
%K nonn,base,easy
%O 0,3
%A _Filipi R. de Oliveira_, Apr 02 2014