

A295266


Positive integers whose squares can be represented as the sum or difference of 3smooth numbers.


0




OFFSET

1,2


COMMENTS

In Chapter 7 of de Weger's tract, it is shown that there are no other terms.
More generally, de Weger exposited how one can determine all squares which can be represented as the sum or difference of ksmooth numbers for any given k and determined all integers whose squares can be represented as the sum or difference of 7smooth numbers, among which the largest one is 14117^2 = 199289869 = 3^13 * 5^3  2 * 7^3.


LINKS

Table of n, a(n) for n=1..6.
B. M. M. de Weger, Algorithms for Diophantine Equations, Centrum voor Wiskunde en Informatica, Amsterdam, 1989.


EXAMPLE

a(6) = 17 ; 17^2 = 288 + 1 = 2^5 * 3^2 + 1.


CROSSREFS

Cf. A003586 (3smooth numbers).
Coincides with A192579 and A215658 except the term 1.
Sequence in context: A343537 A192579 A215658 * A059471 A059496 A066814
Adjacent sequences: A295263 A295264 A295265 * A295267 A295268 A295269


KEYWORD

nonn,fini,full


AUTHOR

Tomohiro Yamada, Nov 19 2017


STATUS

approved



