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A101412
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Least number of odd squares that sum to n.
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2
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1, 2, 3, 4, 5, 6, 7, 8, 1, 2, 3, 4, 5, 6, 7, 8, 9, 2, 3, 4, 5, 6, 7, 8, 1, 2, 3, 4, 5, 6, 7, 8, 9, 2, 3, 4, 5, 6, 7, 8, 9, 10, 3, 4, 5, 6, 7, 8, 1, 2, 3, 4, 5, 6, 7, 8, 9, 2, 3, 4, 5, 6, 7, 8, 9, 10, 3, 4, 5, 6, 7, 8, 9, 2, 3, 4, 5, 6, 7, 8, 1, 2, 3, 4, 5, 6, 7, 8, 9, 2, 3, 4, 5, 6, 7, 8, 9, 2, 3, 4, 5, 6, 7, 8, 9
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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LINKS
| Charles R Greathouse IV, Table of n, a(n) for n = 1..10000
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EXAMPLE
| a(13) = 5: 13 = 1+1+1+1+9.
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MAPLE
| A101412 := proc(n) local lsq; lsq := [seq((2*j+1)^2, j=0..floor((sqrt(n)-1)/2))] ; lsq := convert(lsq, set) ; a := n ; for p in combinat[partition](n) do if convert(p, set) minus lsq = {} then a := min(a, nops(p)) ; fi; od: a ; end: for n from 1 do printf("%d, \n", A101412(n)) ; od: [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Aug 08 2009]
## problem has optimal substructure ##
a:= proc(n) option remember; local r;
r:= sqrt(n);
`if` (type(r, integer) and is(r, odd), 1,
min (seq (a(i)+a(n-i), i=1..floor(n/2))))
end:
seq (a(n), n=1..105);
# Alois P. Heinz (heinz(AT)hs-heilbronn.de), Jan 31 2011
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CROSSREFS
| Cf. A002828, A151925.
Sequence in context: A190598 A053844 A010887 * A053830 A033929 A025482
Adjacent sequences: A101409 A101410 A101411 * A101413 A101414 A101415
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KEYWORD
| nonn,easy
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com), Aug 08 2009
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EXTENSIONS
| More terms from R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Aug 08 2009
More terms from Alois P. Heinz (heinz(AT)hs-heilbronn.de), Jan 30 2011
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