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URL: https://oeis.org/A026100

⇱ A026100 - OEIS

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A026100
a(n) = number of the column of A026098 that contains n.
1
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
1,2
LINKS
PROG
(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.
CROSSREFS
Cf. A026098.
Sequence in context: A277892 A214743 A331179 * A059127 A319494 A105609
KEYWORD
nonn,look
EXTENSIONS
a(27) onward corrected by Sean A. Irvine, Sep 15 2019
STATUS
approved