

A239203


Numbers k such that k+x+y is a square and k+u+v is a triangular number, where x and y are the two squares nearest to k, while u and v are the two triangular numbers nearest to k.


0




OFFSET

1,2


COMMENTS

Intersection of A239071 and A238489.


LINKS

Table of n, a(n) for n=1..6.


EXAMPLE

11 is in the sequence because the two squares nearest to 11 are 9 and 16 and 11+9+16=36 is a square, and also the two triangular numbers nearest to 11 are 10 and 15, and 11+10+15=36 is a triangular number.
Similarly, 218987 is in the sequence because 218987+467^2+468^2=656100 is a square, and 218987+triangular(661)+triangular(662)=657231 is a triangular number.


CROSSREFS

Cf. A000217, A000290, A238489, A239071.
Sequence in context: A144837 A324267 A085017 * A098880 A076173 A100108
Adjacent sequences: A239200 A239201 A239202 * A239204 A239205 A239206


KEYWORD

nonn,hard,more


AUTHOR

Alex Ratushnyak, Mar 12 2014


EXTENSIONS

a(5)a(6) from Lars Blomberg, Jan 12 2016


STATUS

approved



