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%I #9 Dec 18 2014 19:05:00
%S 36,66,78,120,210,276,300,378,528,630,666,780,820,990,1128,1176,1326,
%T 1540,1596,1770,1830,2016,2080,2346,2556,2628,2850,3160,3240,3486,
%U 3570,3828,4095,4278,4560,4656,4950,5460,5778,5886,6216,6328,6786,7140,7260
%N Abundant triangular numbers.
%H Harvey P. Dale, <a href="/A074315/b074315.txt">Table of n, a(n) for n = 1..1000</a>
%F Intersection of A000217 and A005101. - _Michel Marcus_, Mar 10 2013
%e a(2)=66 because sum of aliquot divisors of 66 (which is a triangular number) is 1+2+3+6+11+22+33=78 which is more than 66, hence it is abundant. 66 is 2nd abundant triangular number.
%t Select[Accumulate[Range[150]],Total[Divisors[#]]>2#&] (* _Harvey P. Dale_, Dec 18 2014 *)
%o (PARI) listA074315(m) = {for (i=1, m, t = i*(i+1)/2; if (sigma(t) > 2*t, print1(t, ", ")););} \\ up to the m-th triangular number; _Michel Marcus_, Mar 10 2013
%K base,nonn
%O 1,1
%A _Shyam Sunder Gupta_, Sep 22 2002
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