A026100 a(n) = number of the column of A026098 that contains n.

1, 2, 1, 3, 1, 2, 1, 4, 3, 2, 1, 4, 1, 2, 3, 5, 1, 5, 1, 4, 3, 2, 1, 6, 5, 2, 6, 4, 1, 7, 1, 8, 3, 2, 5, 7, 1, 2, 3, 6, 1, 6, 1, 4, 7, 9, 1, 8, 7, 8, 3, 4, 1, 9, 5, 10, 3, 2, 1, 9, 1, 11, 8, 12, 5, 6, 1, 4, 2, 9, 1, 10, 1, 2, 10, 4, 7, 6, 1, 11, 11, 13, 1, 10, 5, 14, 3, 8, 1, 12, 7, 3, 2, 15, 5, 13, 1, 11, 9, 12

Offset: 1

Author

Clark Kimberling

Keywords

• nonn
• look

Links

• Antti Karttunen, Table of n, a(n) for n = 1..19477

Crossrefs

Cf. A026098.

Programs

PARI

getrow(n, all) = {if (n==1, return ([1])); if (n==2, return ([3, 2])); my(row = vector(n)); row[1] = prime(n); for (k=2, n, my(ok = 0, m = 1, val); until(ok, val = m*prime(n+1-k); if (!setsearch(all, val) && !setsearch(Set(row), val), ok = 1); m++; ); row[k] = val; ); return (row); };
A026100list(up_to_row) = { my(all = [], m = Map(), lista = List([]), u); for(n=1, up_to_row, my(row = getrow(n, all)); for(k=1, n, mapput(m,row[k],k)); all = Set(concat(all, row))); for(n=1,oo,if(mapisdefined(m,n,&u), listput(lista,u), if(isprime(n)&&(n>2),listput(lista,1), return(Vec(lista))))); };
v026100 = A026100list(1200);
A026100(n) = v026100[n]; \\ Antti Karttunen, Jan 18 2020, after program in A026098 provided by Michel Marcus.

Extensions

a(27) onward corrected by Sean A. Irvine, Sep 15 2019