A280635 -id:A280635 - cp's OEIS frontend

A088294 Primes in which the digit string can be partitioned into three parts such that third (least significant) part is the product of the first two.

199, 313, 919, 7321, 7963, 11717, 11777, 12323, 13339, 14747, 15959, 16363, 17117, 17351, 18181, 18787, 21121, 23369, 27127, 29129, 29387, 31393, 31751, 31957, 32369, 32987, 39139, 41141, 47147, 51151, 59159, 71171, 81181, 87187, 89189

Offset: 1

Amarnath Murthy, Sep 30 2003

Primes in A280635. - Randy L. Ekl, Jan 09 2017

			17351 is a member as it can be partitioned as (17, 3, 51) and 17*3 = 51.

Cf. A088291, A088292, A088293, A280635, A280636.

More terms from David Wasserman, Aug 04 2005

Offset changed to 1 by Michel Marcus, Jan 08 2017

A280636 Semiprime numbers whose digit string can be partitioned into three parts such that the product of the first two parts equals the third part.

Original entry on oeis.org

111, 122, 133, 155, 166, 177, 326, 339, 515, 717, 818, 2918, 3721, 5315, 6742, 7214, 7642, 9327, 9763, 11111, 11333, 11555, 12929, 13333, 13535, 13565, 13791, 13939, 14114, 14141, 14242, 14545, 15115, 15151, 15353, 15454, 15757, 16161, 16565

Offset: 1

Randy L. Ekl, Jan 06 2017

Could be called semiprime area numbers. If the first set of digits of the number is considered the length, the second set of digits of the number is considered the width, and the final set of digits of the number is considered the area, then length * width = area.

			2918 is semiprime (2*1459) and an area number (2*9 = 18).
6742 is semiprime (2*3371) and an area number (6*7 = 42).
Leading zeros are not allowed.

Cf. A088294, A280635.

A001358 INTERSECT A280635.

A280732 Numbers whose digit string can be partitioned into three nonempty parts a <= b <= c such that a*b = c.

Original entry on oeis.org

111, 122, 133, 144, 155, 166, 177, 188, 199, 224, 236, 248, 339, 2510, 2612, 2714, 2816, 2918, 3412, 3515, 3618, 3721, 3824, 3927, 4416, 4520, 4624, 4728, 4832, 4936, 5525, 5630, 5735, 5840, 5945, 6636, 6742, 6848, 6954, 7749, 7856, 7963, 8864, 8972, 9981

Offset: 1

N. J. A. Sloane, Jan 10 2017

The parts may not start with 0.

			For n = 2|4|8: 2 <= 4 <= 8, and 2*4=8, so 248 is a term.
For n = 5|9|45: 5 <= 9 <= 45, and 5*9=45, so 5945 is a term.

Lars Blomberg, Table of n, a(n) for n = 1..10000

A subset of A280635. Cf. also A280733.

More terms from Lars Blomberg, Jan 11 2017

A280733 Numbers whose digit string can be partitioned into three nonempty parts a < b <= c such that a*b = c.

Original entry on oeis.org

122, 133, 144, 155, 166, 177, 188, 199, 236, 248, 2510, 2612, 2714, 2816, 2918, 3412, 3515, 3618, 3721, 3824, 3927, 4520, 4624, 4728, 4832, 4936, 5630, 5735, 5840, 5945, 6742, 6848, 6954, 7856, 7963, 8972, 11010, 11111, 11212, 11313, 11414, 11515, 11616, 11717

Offset: 1

N. J. A. Sloane, Jan 10 2017

The parts may not start with 0.

			For n = 3|4|12: 3 < 4 <= 12, and 3*4=12, so 3412 is a term.
For n = 1|10|10: 1 < 10 <= 10, and 1*10=10, so 11010 is a term.

Lars Blomberg, Table of n, a(n) for n = 1..10000

A subset of A280635 and A280732.

More terms from Lars Blomberg, Jan 11 2017

cp's OEIS Frontend

A088294 Primes in which the digit string can be partitioned into three parts such that third (least significant) part is the product of the first two.

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A280636 Semiprime numbers whose digit string can be partitioned into three parts such that the product of the first two parts equals the third part.

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A280732 Numbers whose digit string can be partitioned into three nonempty parts a <= b <= c such that a*b = c.

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A280733 Numbers whose digit string can be partitioned into three nonempty parts a < b <= c such that a*b = c.

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