OFFSET
1,1
EXAMPLE
a(1) = 2 = 1+1.
25 is a term because 25 = 16 + 9 = 10 + 15 = 4 + 21, and 16, 9, 4 are squares, 10, 15, 21 are triangular numbers.
CROSSREFS
KEYWORD
nonn
AUTHOR
Alex Ratushnyak, Nov 03 2015
STATUS
approved