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
Keywords
Examples
36963^2 = 1110^3-111^3 = 1332^3-999^3.
Links
- Donovan Johnson, Table of n, a(n) for n = 1..100
Programs
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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
Extensions
Corrected and extended by Ray Chandler, Dec 01 2008
Offset corrected by Donovan Johnson, Oct 29 2013