OFFSET
1,1
COMMENTS
There are 718 such numbers up to 2*10^9, the last one in this range being 99570649.
It is known that each natural number can be written as the sum of two squares and a triangular number. I believe that the sequence only has 718 terms as found by _Giovanni Resta and listed in the b-file. - Zhi-Wei Sun, Apr 15 2020
LINKS
Zhi-Wei Sun, Table of n, a(n) for n = 1..718
Zhi-Wei Sun, Mixed sums of squares and triangular numbers, Acta Arith. 127(2007), 103-113.
MATHEMATICA
TQ[n_]:=TQ[n]=IntegerQ[Sqrt[8n+1]];
tab={}; Do[Do[If[TQ[n-x^4-y^2], Goto[aa]], {x, 0, n^(1/4)}, {y, 0, Sqrt[n-x^4]}]; tab=Append[tab, n]; Label[aa], {n, 0, 4114}]; Print[tab] (From Zhi-Wei Sun)
CROSSREFS
KEYWORD
nonn
AUTHOR
Giovanni Resta, Jan 15 2006
EXTENSIONS
Definition corrected by Giovanni Resta, Aug 17 2011
STATUS
approved