A262724 Triangular numbers representable as 3^x + y^3.

1, 3, 10, 28, 36, 91, 1081, 2278, 2926, 8001, 46665, 5639761, 10911456, 166066200, 341532180, 3137785371, 1647882316985625, 875366737297292691171, 465198187808352499674075441

Offset: 1

Author

Alex Ratushnyak, Sep 28 2015

Keywords

• nonn
• hard

Comments

Any further terms are greater than 10^30. - Charles R Greathouse IV, Oct 02 2015

Crossrefs

Cf. A000217, A225390, A226499, A227027, A259745, A259746, A262242, A262251.

Programs

PARI

list(lim)=my(v=List(),X,t); for(x=0,logint(lim\=1,3), X=3^x; for(y=0, sqrtnint(lim-X,3), if(ispolygonal(t=X+y^3,3), listput(v,t)))); Set(v) \\ Charles R Greathouse IV, Sep 28 2015

Extensions

a(17)-a(19) from Charles R Greathouse IV, Sep 28 2015