A247947 -id:A247947 - cp's OEIS frontend

A274948 Irregular triangle read by rows: T(n,k) (n>=1, 0 <= k <= n^2) = maximal number of squares not attacked by any arrangement of k queens on an n X n board = n^2 - A274947(n,k).

1, 0, 4, 0, 0, 0, 0, 9, 2, 1, 0, 0, 0, 0, 0, 0, 0, 16, 6, 3, 2, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 25, 12, 7, 5, 4, 3, 2, 2, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0

Offset: 1

N. J. A. Sloane, Jul 27 2016

For further information see A274947, which is the main entry for this problem.

			The triangle begins:
1, 0,
4, 0, 0, 0, 0,
9, 2, 1, 0, 0, 0, 0, 0, 0, 0,
16, 6, 3, 2, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
25, 12, 7, 5, 4, 3, 2, 2, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
36, 20, 13, 9, 8, 6, 5, 4, 4, 3, 2, 2, 2, 2, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
...

Cf. A247947, A250000.

Corrections and more terms from Andrey Zabolotskiy, Jul 29 2016

A247948 Five-digit odd semiprimes with all digits distinct.

Original entry on oeis.org

10237, 10239, 10249, 10265, 10279, 10297, 10327, 10345, 10347, 10349, 10367, 10379, 10389, 10397, 10423, 10435, 10473, 10483, 10489, 10493, 10495, 10497, 10523, 10537, 10543, 10547, 10573, 10579, 10583, 10587, 10623, 10637, 10643, 10645, 10649

Offset: 1

K. D. Bajpai, Sep 27 2014

There are exactly 4858 five-digit odd semiprimes with all digits distinct. The last few terms of the sequence are: 98501, 98503, 98517, 98521, 98531, 98537, 98567, 98603, 98607, 98617, 98635, 98647, 98653, 98657, 98671, 98701, 98723, 98741, 98743, 98751, 98765.

See the link with the b-file for all 4858 entries.

			a(1) = 10237 = 29 * 353 is the smallest five-digit odd semiprime with all digits distinct.
a(4858) = 98765 = 5 * 19753 is the largest five-digit odd semiprime with all digits distinct.

K. D. Bajpai, Table of n, a(n) for n = 1..4858

Cf. A001358, A046315, A074671, A074673, A235690, A247947.

c = 0; Do[If[Length[Union[IntegerDigits[n]]] == 5 && PrimeOmega[n] == 2, c++; Print[c, "  ", n]], {n, 10001, 99999, 2}]

cp's OEIS Frontend

A274948 Irregular triangle read by rows: T(n,k) (n>=1, 0 <= k <= n^2) = maximal number of squares not attacked by any arrangement of k queens on an n X n board = n^2 - A274947(n,k).

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