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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 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

LINKS

Harvey P. Dale, Table of n, a(n) for n = 0..1000

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

Adjacent sequences:  A014130 A014131 A014132 * A014134 A014135 A014136

KEYWORD

nonn

AUTHOR

N. J. A. Sloane.

STATUS

approved

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Last modified June 16 04:56 EDT 2021. Contains 345056 sequences. (Running on oeis4.)