OFFSET
1,2
LINKS
EXAMPLE
n=13->'1101', 13*(13+1)/2=91->'1011011': '..1101.', therefore 13 is a term.
MATHEMATICA
Select[Range[15000], SequenceCount[IntegerDigits[(#(#+1))/2, 2], IntegerDigits[ #, 2]]>0&] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Nov 20 2019 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Reinhard Zumkeller, Apr 12 2004
STATUS
approved