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A014133
Sum of a square and a triangular number.
5
0, 1, 2, 3, 4, 5, 6, 7, 9, 10, 11, 12, 14, 15, 16, 17, 19, 21, 22, 24, 25, 26, 28, 29, 30, 31, 32, 35, 36, 37, 39, 40, 42, 44, 45, 46, 49, 50, 51, 52, 53, 54, 55, 56, 57, 59, 61, 64, 65, 66, 67, 70, 71, 72, 74, 75, 77, 78, 79, 80, 81, 82, 84, 85, 87, 91
OFFSET
0,3
LINKS
FORMULA
{k: A101428(k) > 0} .- R. J. Mathar, Apr 28 2020
MAPLE
isA014133 := proc(n)
local c, t ;
for c from 0 do
t := c*(c+1)/2 ;
if t > n then
return false;
end if;
if issqr(n-t) then
return true;
end if;
end do:
end proc:
for n from 0 to 100 do
if isA014133(n) then
printf("%d, ", n) ;
end if;
end do: # R. J. Mathar, Oct 11 2014
MATHEMATICA
With[{nn=20}, Select[Union[Flatten[Outer[Plus, Range[0, nn]^2, Accumulate[ Range[ 0, nn]]]]], #<=(nn(nn+1))/2&]] (* Harvey P. Dale, Dec 29 2019 *)
CROSSREFS
Cf. A014134 (complement).
Sequence in context: A214879 A187226 A026470 * A070115 A073571 A328242
KEYWORD
nonn
AUTHOR
STATUS
approved