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A101428
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Number of ways to write n as an ordered sum x^2+T_y of a square and a triangular number, allowing x=0 or T_y=0.
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0
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1, 2, 1, 1, 2, 1, 1, 2, 0, 1, 3, 1, 1, 0, 1, 2, 2, 1, 0, 3, 0, 1, 2, 0, 1, 2, 2, 0, 2, 1, 1, 2, 1, 0, 0, 1, 2, 4, 0, 1, 2, 0, 1, 0, 1, 2, 3, 0, 0, 2, 1, 1, 2, 1, 1, 2, 1, 1, 0, 2, 0, 2, 0, 0, 4, 1, 1, 2, 0, 0, 4, 1, 1, 0, 1, 1, 0, 1, 1, 2, 1, 2, 3, 0, 1, 2, 0, 2, 0, 0, 0, 4, 2, 0, 2, 1, 1, 0, 0
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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EXAMPLE
| Examples: n=1 gives the a(1)=2 cases 1=1+0=0+1; a(26)=2 because 26=25+1=16+10.
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MAPLE
| A000217 := proc(n) n*(n+1)/2 ; end:
A := proc(n)
local a, y, t ;
a := 0 ;
for y from 0 do
t := A000217(y) ;
if n-t < 0 then
RETURN(a) ;
else
if issqr(n-t) then
a := a+1 ;
fi;
fi;
od:
end:
for n from 0 to 100 do printf("%a, ", A(n)) ; od:
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CROSSREFS
| Cf. A000925, A115171, A115172, A115173, A115174, A115175, A115176, A115177, A144642.
Sequence in context: A140218 A193805 A159704 * A023586 A023584 A015182
Adjacent sequences: A101425 A101426 A101427 * A101429 A101430 A101431
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KEYWORD
| nonn
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AUTHOR
| Richard Mathar (mathar(AT)strw.leidenuniv.nl), Jan 03 2009
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