This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
From _M. F. Hasler_, Nov 27 2018: (Start) The array starts: 0 1 2 3 4 5 6 ... 1 3 8 9 10 11 30 ... 2 7 26 27 28 29 ... 3 9 32 33 34 ... 4 13 50 51 ... (...) (End) A(4,3) = 51 which has a factorial expansion '2011' (2*24+0*6+1*2+1*1), a concatenation of factorial expansions of 4, '20' and of 3, '11'. Similarly, A(3,4) = 34 which has a factorial expansion '1120' (1*24+1*6+2*2+0*1). See A085217 for the corresponding factorial expansions.
A085215(x,y)=A322001(eval(Str(A007623(x),A007623(y)))) \\ M. F. Hasler, Nov 27 2018. N.B. This has the same caveat as Hasler's formula. See below for program that is correct for all x, y >= 0. - Antti Karttunen, Mar 24 2025
up_to = 78; A085215sq(x,y) = { my(i=2,j=2,z=0,f=1); while(y>0, z += (y%i)*f; f *= i; y \= i; i++); while(x>0, z += (x%j)*f; f *= i; x \= j; i++; j++); (z); }; A085215list(up_to) = { my(v = vector(up_to), i=0); for(a=0, oo, for(col=0, a, i++; if(i > up_to, return(v)); v[i] = A085215sq(a-col, col))); (v); }; v085215 = A085215list(up_to); A085215(n) = v085215[1+n]; \\ Antti Karttunen, Mar 24 2025
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