

A004441


Numbers that are not the sum of 4 distinct nonzero squares.


4



1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 31, 32, 33, 34, 35, 36, 37, 38, 40, 41, 42, 43, 44, 45, 47, 48, 49, 52, 53, 55, 56, 58, 59, 60, 61, 64, 67, 68
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OFFSET

1,2


COMMENTS

It has been shown that 157 is the last odd number in this sequence. Beyond 157, the terms grow exponentially.  T. D. Noe, Apr 07 2007
Taking a(86) to a(120) as initial terms, A004441(n) satisfies the thirty fifth order recurrence relation u(n)=4u(n35).  Ant King, Aug 13 2010


LINKS

T. D. Noe, Table of n, a(n) for n=1..1000 (using A004195 and A004196)
Paul T. Bateman, Adolf J. Hildebrand and George B. Purdy, Sums of distinct squares, Acta Arith. 67 (1994), 349380.
H. D. Nguyen, D. Taggart, Mining the OEIS: Ten Experimental Conjectures, 2013. Mentions this sequence.  From N. J. A. Sloane, Mar 16 2014
Index entries for sequences related to sums of squares


MATHEMATICA

data1=Reduce[w^2+x^2+y^2+z^2==# && 0<w<x<y<z<#, {w, x, y, z}, Integers]&/@Range[1000]; data2=If[Head[ # ]===And, 1, Length[ # ]] &/@data1; DeleteCases[Table[If[data2[[k]]>0, 0, k], {k, 1, Length[data2]}], 0] (* Ant King, Aug 13 2010 *)


CROSSREFS

Cf. A004195, A004196, A004433 (complement).
Sequence in context: A273888 A192218 A070915 * A004438 A109425 A226537
Adjacent sequences: A004438 A004439 A004440 * A004442 A004443 A004444


KEYWORD

nonn


AUTHOR

N. J. A. Sloane


STATUS

approved



