The OEIS is supported by the many generous donors to the OEIS Foundation.

 Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 60th year, we have over 367,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”). Other ways to Give
 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A004214 Positive numbers that are not the sum of three nonzero squares. (Formerly M0959) 19
 1, 2, 4, 5, 7, 8, 10, 13, 15, 16, 20, 23, 25, 28, 31, 32, 37, 39, 40, 47, 52, 55, 58, 60, 63, 64, 71, 79, 80, 85, 87, 92, 95, 100, 103, 111, 112, 119, 124, 127, 128, 130, 135, 143, 148, 151, 156, 159, 160, 167, 175, 183, 188, 191, 199, 207, 208, 215, 220, 223, 231 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Not of the form x^2 + y^2 + z^2 with x, y, z >= 1. Complement of A000408, but skipping the zero. - R. J. Mathar, Nov 23 2006 A025427(a(n)) = 0. - Reinhard Zumkeller, Feb 26 2015 REFERENCES N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence). LINKS Ray Chandler, Table of n, a(n) for n = 1..10000 David S. Bettes, Letter to N. J. A. Sloane, Nov 05 1976. Index entries for sequences related to sums of squares EXAMPLE The smallest numbers that are the sums of 3 nonzero squares are 3=1+1+1, 6=1+1+4, 9=1+4+4, etc. MAPLE gf := sum(sum(sum(q^(x^2+y^2+z^2), x=1..25), y=1..25), z=1..25): s := series(gf, q, 500): for n from 1 to 500 do if coeff(s, q, n)=0 then printf(`%d, `, n) fi:od: MATHEMATICA f[n_] := Flatten[Position[Take[Rest[CoefficientList[Sum[x^(i^2), {i, n}]^3, x]], n^2], 0]]; f[16] (* Ray Chandler, Dec 06 2006 *) PROG (PARI) isA000408(n)={ local(a, b) ; a=1; while(a^2+1

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified December 8 15:21 EST 2023. Contains 367680 sequences. (Running on oeis4.)