A307746 Triangle read by rows, obtained by omitting all the 1's from the triangle in A307641 (except for the first row).

1, 2, 3, 2, 2, 5, 2, 3, 7, 2, 2, 2, 3, 3, 2, 5, 11, 2, 3, 2, 13, 2, 7, 3, 5, 2, 2, 2, 2, 17, 2, 3, 3, 19, 2, 2, 5, 3, 7, 2, 11, 23, 2, 3, 2, 2, 5, 5, 2, 13, 3, 3, 3, 2, 2, 7, 29, 2, 3, 5, 31, 2, 2, 2, 2, 2, 3, 11, 2, 17, 5, 7, 2, 3, 2, 3, 37, 2, 19, 3, 13

Offset

1,2

Comments

Has same shape as the triangle in A027746. The first difference occurs at row 12.

Links

Michel Marcus, Rows n=1..3000 of triangle, flattened (first 131 rows from I. V. Serov)

Formula

Row(i) = {d|i, A014963(d) > 1} A014963(d).

For i > 1, T(i, A001222(i)) = A088387(i). This is the last term of the i-th row.

Example

Triangle begins:
1;
2;
3;
2, 2;
5;
2, 3;
7;
2, 2, 2;
3, 3;
2, 5;
11;
2, 3, 2;
...

Prog

(PARI) f(n)=ispower(n, , &n); if(isprime(n), n, 1); \\ A014963
row(n) = if (n==1, [1], my(d=divisors(n)); select(x->x!=1, vector(#d, k, f(d[k]))));
tabl(nn) = for (n=1, nn, print(row(n))); \\ Michel Marcus, Apr 27 2019

Crossrefs

Cf. A088387, A014963, A027746, A307641.

Sequence in context: A225243 A207338 A027746 * A348477 A240230 A238689

Adjacent sequences: A307743 A307744 A307745 * A307747 A307748 A307749

Keyword

nonn,tabf

Author

I. V. Serov, Apr 26 2019

Status

approved