OFFSET
1,2
LINKS
Colin Barker, Table of n, a(n) for n = 1..1000
MATHEMATICA
Nest[Append[#, Last@ # + Total@ Select[#, IntegerQ@ First@ Values@ Last@ Solve[x (x + 1)/2 == #, x] &]] &, {1}, 44] (* Michael De Vlieger, Sep 24 2017 *)
PROG
(PARI) vector(100, n, if(n==1, a_n_1=sum_=1, a_n_1+=sum_; if(ispolygonal(a_n_1, 3), sum_+=a_n_1)); a_n_1) \\ Colin Barker, Feb 19 2015
CROSSREFS
KEYWORD
nonn
AUTHOR
Leroy Quet, Jun 07 2007
EXTENSIONS
More terms from Robert Gerbicz, Jun 10 2007
STATUS
approved