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%I #8 Aug 21 2023 21:56:28
%S 1,2,5,9,5,11,18,2,11,21,32,44,11,25,40,56,73,16,35,55,76,98,10,34,59,
%T 85,112,140,15,45,76,108,141,175,6,42,79,117,156,196,237,18,61,105,
%U 150,196,243,291,15,65,116,168,221,275,330,386,47,105,164,224,285,347,410
%N Fill a triangular array by rows by writing numbers 1 up to b(0), 1 up to b(1), etc., where b(n) are the 9-gonal (nonagonal) numbers. The final elements of the rows form a(n).
%Y Cf. A001106, A064766, A064865, A065221-A065224, A065226-A065234.
%K easy,nonn
%O 0,2
%A _Floor van Lamoen_, Oct 22 2001
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