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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).
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%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