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%I #17 Aug 26 2019 05:18:18
%S 1,121,187,14014
%N Numbers n such that product of n with sum of next n consecutive integers is palindromic.
%C Also, number n such that n^2*(3*n+1)/2 is palindromic.
%C No additional terms below 10^10. - _Jens Voß_, Feb 20 2009
%C a(5) > 3.7*10^12, if it exists. - _Giovanni Resta_, Aug 26 2019
%e 187 * (188+189+...+373+374) = 187 * 52547 = palindrome 9826289.
%p A036659 := proc(n) n^2*(3*n+1)/2 ; end: isA002113 := proc(n) local b10,i ; b10 := convert(n,base,10) ; for i from 1 to nops(b10)/2 do if op(i,b10) <> op(-i,b10) then RETURN(false) ; fi ; od ; RETURN(true) ; end: for n from 1 to 1000000 do c := A036659(n) : if isA002113(c) then print(n) ; fi ; od : # _R. J. Mathar_, Jun 26 2007
%Y Cf. A036659, A037051.
%K nonn,base,hard,more
%O 1,2
%A _Patrick De Geest_, Jan 04 1999