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%I #23 Sep 08 2022 08:44:32
%S 0,1,3,6,1,51,12,82,63,54,55,66,87,19,501,21,631,351,171,91,12,132,
%T 352,672,3,523,153,873,604,534,564,694,825,165,595,36,666,307,147,87,
%U 28,168,309,649,99,5301,1801,8211,6711,5221,5721,6231,8731,1341,5841,451
%N Triangular numbers written backwards.
%H Alois P. Heinz, <a href="/A004158/b004158.txt">Table of n, a(n) for n = 0..10000</a>
%F a(n) = A004086(A000217(n)). - _Michel Marcus_, Apr 05 2014
%p a:= n-> (s-> parse(cat(s[-i]$i=1..length(s))))(""||(n*(n+1)/2)):
%p seq(a(n), n=0..60); # _Alois P. Heinz_, Apr 09 2015
%t Table[FromDigits[Reverse[IntegerDigits[n (n + 1) / 2]]], {n, 0, 50}] (* _Vincenzo Librandi_, Jan 21 2016 *)
%o (Magma) [Seqint(Reverse(Intseq(Binomial((n+1),2)))): n in [0..60]]; // _Vincenzo Librandi_, Jan 21 2016
%K nonn,base,look
%O 0,3
%A _N. J. A. Sloane_
%E Initial 0 and terms after a(46) from _Eric M. Schmidt_, Apr 04 2014
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