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%I #9 May 10 2019 21:48:44
%S 0,3,15,630,1830,2346,4371,5253,5460,19110,98346,478731,519690,
%T 1216020,10669890,266539416,311737965,377836305,4375193196,5476282185,
%U 57391534206,3361994343645,7631474751153,9750146019741,43606139789376,1199784486145710
%N Triangular numbers that remain triangular numbers when their reverse is added.
%F {A000217(i) : A000217(i)+A004158(i) in A000217}. [_R. J. Mathar_, Oct 31 2009]
%e 2346 is a triangular number and 2346 + 6432 = 8778 is also a triangular number.
%p read("transforms"): A000217 := proc(n) n*(n+1)/2 ; end proc:
%p isA000217 := proc(n) issqr( 1+8*n) ; end proc:
%p isA167220 := proc(n) R := digrev(n) ; return isA000217(n) and isA000217(n+R) ; end:
%p for n from 0 to 30000 do T := A000217(n) ; if isA167220(T) then printf("%d,",T) ; end if; od: # _R. J. Mathar_, Oct 31 2009
%K base,nonn
%O 1,2
%A _Claudio Meller_, Oct 30 2009
%E 5 more terms from _R. J. Mathar_, Oct 31 2009
%E a(21)-a(26) from _Donovan Johnson_, Apr 26 2011
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