A353387 a(n) is the least squared distance between 2 points of an n X n grid not occurring between two points of an (n-1) X (n-1) grid.

1, 4, 9, 16, 26, 36, 49, 64, 81, 101, 121, 144, 173, 196, 226, 256, 293, 324, 361, 401, 441, 484, 529, 576, 626, 677, 729, 784, 842, 904, 961, 1024, 1089, 1172, 1226, 1296, 1373, 1444, 1522, 1601, 1697, 1764, 1849, 1936, 2026, 2116, 2209, 2304, 2401, 2504, 2602, 2708

Offset: 2

Author

Hugo Pfoertner, Apr 16 2022

Keywords

• nonn

Crossrefs

Cf. A001105, A001481, A047800.

First column of A353386.

Programs

PARI

a353387(nmax)={my(v=vectorsmall(2*nmax^2)); for(n=1,nmax,my(dfirst=0);
for(k=0,n,my(s=n^2+k^2); if(!v[s],if(!dfirst,print1(s,", ");dfirst=1); v[s]++)))};
a353387(52)