OFFSET
1,2
COMMENTS
EXAMPLE
Triangle A256440 starts:
1;
1, 2;
1, 3, 2;
1, 3, 2, 4;
1, 5, 3, 2, 4;
1, 5, 3, 2, 4, 6;
1, 7, 5, 3, 2, 4, 6;
...
a(1)=1 because row 1 is the first row where 1 is the 1st term of the row.
a(2)=2 because row 2 is the first row where 2 is the 2nd term of the row.
a(3)=5 because row 5 is the first row where 3 is the 3rd term of the row.
PROG
(PARI) posf(n) = {i = n; stop = 0; while (! stop, v = vector(i, k, sigma(k)/k); w = vecsort(v, , 1); pos = posv(n, w); if (pos == n, stop=1, i++); ); i; }
CROSSREFS
KEYWORD
nonn
AUTHOR
Michel Marcus, Mar 30 2015
STATUS
approved