A138615 Numbers of the form n^4 - m^2, where 0 < m < n^2.

7, 12, 15, 17, 31, 32, 45, 49, 56, 60, 65, 71, 72, 77, 80, 87, 96, 97, 112, 127, 135, 140, 141, 156, 161, 175, 184, 192, 199, 207, 220, 225, 231, 240, 241, 247, 252, 255, 264, 272, 285, 287, 301, 320, 335, 336, 337, 369, 375, 376, 391, 396, 400, 429, 449, 455

Offset

1,1

Links

Klaus Brockhaus, Table of n, a(n) for n=1..1000

Example

7 is in the sequence because 2^4 - 3^2 = 7; 127 is in the sequence because 8^4 - 63^2 = 127.

Mathematica

nn=60; Take[Union[Flatten[Table[n^4-m^2, {n, 0, nn}, {m, n^2-1}]]], nn] (* Harvey P. Dale, Mar 04 2013 *)

Prog

(PARI) {z=455; v=[]; n=2; while((p=n^4)-(q=n^2-1)^2<=z, m=q; while(m>0&&(a=p-m^2)<=z, v=concat(v, a); m--); n++); v=listsort(List(v), 1); for(j=1, #v, print1(v[j], ", "))} /* Klaus Brockhaus, May 31 2008 */

Crossrefs

Sequence in context: A145310 A177988 A072834 * A210254 A071780 A353219

Adjacent sequences: A138612 A138613 A138614 * A138616 A138617 A138618

Keyword

nonn

Author

Garrett Webb (garrettwebb(AT)gmail.com), May 14 2008

Extensions

Edited and extended by Klaus Brockhaus, May 31 2008

Status

approved