A051393 Numbers whose square is expressible as the difference of positive cubes in more than one way.

36963, 66248, 157339, 262808, 295704, 519841, 529984, 793117, 990584, 998001, 1258712, 1271403, 1291836, 1788696, 2102464, 2365632, 2688728, 3294486, 3756536, 4158728, 4239872, 4248153, 4620375, 5532247, 5738904, 5938947, 6344936, 6562101, 7095816, 7924672

Offset

1,1

Links

Donovan Johnson, Table of n, a(n) for n = 1..100

Example

36963^2 = 1110^3-111^3 = 1332^3-999^3.

Prog

(PARI) mm=577350; cb=vector(mm); for(i=1, mm, cb[i]=i^3); v=vector(10^6); n=vector(10); c=0; mx=10^12; for(i=1, mm-1, for(j=i+1, mm, s=cb[j]-cb[i]; if(s<=mx, if(issquare(s, &r), v[r]++; if(v[r]==2, c++; n[c]=r)), next(2)))); n=vecsort(n); for(i=1, c, print1(n[i] ", ")) \\ Donovan Johnson, Oct 29 2013

Crossrefs

Cf. A038596, A038597.

Sequence in context: A229509 A223304 A190383 * A233914 A144801 A144812

Adjacent sequences: A051390 A051391 A051392 * A051394 A051395 A051396

Keyword

nonn

Author

Jud McCranie

Extensions

Corrected and extended by Ray Chandler, Dec 01 2008

Offset corrected by Donovan Johnson, Oct 29 2013

Status

approved