A138615 - OEIS

%I #7 Mar 04 2013 14:03:51

%S 7,12,15,17,31,32,45,49,56,60,65,71,72,77,80,87,96,97,112,127,135,140,

%T 141,156,161,175,184,192,199,207,220,225,231,240,241,247,252,255,264,

%U 272,285,287,301,320,335,336,337,369,375,376,391,396,400,429,449,455

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

%H Klaus Brockhaus, <a href="/A138615/b138615.txt">Table of n, a(n) for n=1..1000</a>

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

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

%o (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 */

%K nonn

%O 1,1

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

%E Edited and extended by _Klaus Brockhaus_, May 31 2008