%I #35 Jan 11 2020 21:13:04
%S 1,212,32423,4364634,548696845,651081291281056,7612101512161215101267,
%T 87141218152016201518121478,981614211824202520241821141689,
%U 109181624212824302530242821241618910
%N Construct a triangle with centered rows in which row n contains n copies of n; form the componentwise sum of the first n rows and concatenate these decimal numbers to get a(n).
%C A109242 may be constructed using a similar pyramid algorithm:
%C ....1..........a(1) = 1
%C ...1 1.........a(2) = 111
%C ..1 1 1........a(3) = 11211
%C .1 1 1 1.......a(4) = 1122211
%e ...1................a(1) = 1
%e ..2 2...............a(2) = 212
%e .3 3 3..............a(3) = 32423
%e 4 4 4 4.............a(4) = 4364634
%K nonn,base
%O 1,2
%A _Dave Durgin_, Mar 19 2012
%E Definition edited by _N. J. A. Sloane_, Jan 11 2020