%I #19 Nov 17 2018 22:09:23
%S 0,1,3,6,91,141,192,262,333,414,505,606,717,829,9591,10911,12421,
%T 13941,15561,17281,19092,21012,23032,25152,27273,29593,31923,34443,
%U 36964,39594,42324,45154,48075,51015,54145,57276,60606,63937,67377,70917,74548,78288
%N a(n) = T(n) concatenated with reverse(T(n)) divided by 11, where T(n) is the n-th triangular number.
%e a(12) = 7887/11 = 717.
%p a:= n-> (t-> parse(cat(t, (s-> seq(s[-i], i=1..length(s)))(""||t)))/11)(n*(n+1)/2):
%p seq(a(n), n=0..50); # _Alois P. Heinz_, Nov 17 2018
%t r[n_] := FromDigits[Join[IntegerDigits[n], Reverse[IntegerDigits[n]]]]; Do[k = n*(n+1)/2; Print[r[k]/11], {n, 0, 50}] (* _Ryan Propper_, Sep 26 2005 *)
%t f[n_]:=Module[{idn=IntegerDigits[n]},FromDigits[Join[idn,Reverse[ idn]]] /11]; f/@Accumulate[Range[0,40]] (* _Harvey P. Dale_, Sep 15 2011 *)
%Y Cf. A000217, A004086.
%K base,nonn
%O 0,3
%A _Amarnath Murthy_ and Meenakshi Srikanth (menakan_s(AT)yahoo.com), May 23 2003
%E More terms from _Ryan Propper_, Sep 26 2005
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