A265999 -id:A265999

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A266000

Numbers n such that the symmetric representation of sigma(n) has at least two parts of distinct size.

+10
1

9, 21, 25, 27, 33, 35, 39, 45, 49, 50, 51, 55, 57, 63, 65, 69, 70, 75, 77, 81, 85, 87, 91, 93, 95, 98, 99, 105, 110, 111, 115, 117, 119, 121, 123, 125

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OFFSET

1,1

COMMENTS

In other words: numbers n such that the symmetric representation of sigma(n) has at least two parts with distinct number of cells.

For more information about the symmetric representation of sigma see A237270 and A237593.

LINKS

Table of n, a(n) for n=1..36.

EXAMPLE

The symmetric representation of sigma(9) = 13 in the first quadrant looks like this:

._ _ _ _ _ 5

|_ _ _ _ _|

. |_ _ 3

. |_ |

. |_|_ _ 5

. | |

. . . . . . . . |_| . . x

There are three parts: 5 + 3 + 5 = 13, so 9 is in the sequence because the structure contains at least two parts of distinct size.

CROSSREFS

Complement of A265999.

Cf. A000203, A196020, A235791, A236104, A237270, A237271, A237591, A237593, A239660, A239931-A239934, A245092, A262626.

KEYWORD

nonn,more

AUTHOR

Omar E. Pol, Dec 19 2015

STATUS

approved

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