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 itertools import combinations_with_replacement def A225254(n): return len({sum(x) for x in combinations_with_replacement({i*j for i in range(n+1) for j in range(i+1)},3)}) # Chai Wah Wu, Oct 13 2023
a(3) = 16 as the possible products i*j where 0 <= i, j <= 3 are 0, 1, 2, 3, 4, 6, 9. From these numbers we can find the 16 distinct sums, listed with a few examples, 0, 1, 2, 3, 4, 5, 6, 7 = 3+4, 8, 9, 10, 11, 12 = 6+6, 13 = 4+9, 15, 18. - _David A. Corneth_, Sep 07 2023
a(n) = #setbinop((x,y)->x+y, setbinop((x,y)->x*y, [0..n])); \\ Michel Marcus, Sep 06 2023
\\ See PARI link. David A. Corneth, Sep 07 2023
from itertools import combinations_with_replacement def A225253(n): return len({x+y for x,y in combinations_with_replacement({i*j for i in range(n+1) for j in range(i+1)},2)}) # Chai Wah Wu, Oct 13 2023
a(n) = my(v=setbinop((x,y)->x+y, setbinop((x,y)->x*y, [0..n]))); for(k=0, vecmax(v)+1, if (!vecsearch(v, k), return(k))); \\ Michel Marcus, Sep 07 2023
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