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A180175
Diagonal sums of A164844.
0
1, 10, 101, 1011, 10112, 101123, 1011235, 10112358, 101123593, 1011235951, 10112359544, 101123595495, 1011235955039, 10112359550534, 101123595505573, 1011235955056107, 10112359550561680, 101123595505617787, 1011235955056179467, 10112359550561797254
OFFSET
1,2
COMMENTS
Sums are built along inclined lines through the triangle with (1,2)-steps in the (row,column) indices. - R. J. Mathar, Aug 19 2010
FORMULA
From R. J. Mathar, Aug 19 2010: (Start)
G.f.: ( 1-x ) / ( (10*x-1)*(x^2+x-1) ).
a(n) = +11*a(n-1) -9*a(n-2) -10*a(n-3).
a(n) = (90*10^n -A022100(n))/89. (End)
EXAMPLE
From R. J. Mathar, Aug 19 2010: (Start)
One example is a(5), the sum of numbers in parentheses:
1;
1, 10;
(1), 11, 100;
1, 12, (111) ; 1000;;
1, 13, 123 ; 1111, (10000); (End)
CROSSREFS
Sequence in context: A283508 A261200 A175541 * A267526 A261199 A041041
KEYWORD
nonn,easy
AUTHOR
Mark Dols, Aug 15 2010
EXTENSIONS
More terms from R. J. Mathar, Aug 19 2010
STATUS
approved