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The sum of 2 or more consecutive nonzero triangular numbers.
3

%I #14 Apr 29 2022 03:48:04

%S 4,9,10,16,19,20,25,31,34,35,36,46,49,52,55,56,64,74,80,81,83,84,85,

%T 100,109,110,116,119,120,121,130,136,144,145,155,161,164,165,166,169,

%U 185,196,199,200,202,210,216,219,220,225,230,235,244,251

%N The sum of 2 or more consecutive nonzero triangular numbers.

%H Vincenzo Librandi, <a href="/A050943/b050943.txt">Table of n, a(n) for n = 0..7350</a> (missing terms inserted by _Sean A. Irvine_, Apr 28 2022)

%t nn=20;With[{trnos=Accumulate[Range[nn]]},Union[Flatten[Table[ Total/@ Partition[ trnos,n,1],{n,2,nn}]]]] (* _Harvey P. Dale_, Jul 25 2014 *)

%Y Cf. A050942.

%K nonn

%O 0,1

%A _N. J. A. Sloane_, Jan 02 2000