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A319796 Even numbers that have middle divisors. 9
2, 4, 6, 8, 12, 16, 18, 20, 24, 28, 30, 32, 36, 40, 42, 48, 50, 54, 56, 60, 64, 66, 70, 72, 80, 84, 88, 90, 96, 98, 100, 104, 108, 110, 112, 120, 126, 128, 130, 132, 140, 144, 150, 154, 156, 160, 162, 168, 170, 176, 180, 182, 190, 192, 196, 198, 200, 204, 208, 210, 216, 220, 224, 228, 234, 238, 240, 242, 252, 256 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Even numbers k such that the symmetric representation of sigma(k) has an odd number of parts.

An even number A005843 is in this sequence iff A067742(t) != 0.

For the definition of middle divisors, see A067742.

For more information about the symmetric representation of sigma(k) see A237593.

LINKS

Table of n, a(n) for n=1..70.

EXAMPLE

6 is in the sequence because it's an even number and the symmetric representation of sigma(6) = 12 has an odd number of parts (more exactly only one part), as shown below:

.    _ _ _ _

.   |_ _ _  |_ 12

.         |   |_

.         |_ _  |

.             | |

.             | |

.             |_|

.

Also 50 is in the sequence because it's an even number and the symmetric representation of sigma(50) = 93 has an odd number of parts (more exactly three parts), they are [39, 15, 39].

CROSSREFS

Intersection of A005843 and A071562.

Cf. A000203, A067742, A071090, A236104, A237270, A237271, A237593, A239932, A239934, A240542, A245092, A280919, A281007, A296508, A299761, A299777, A303297, A319529, A319801, A319802.

Sequence in context: A058825 A087086 A301587 * A103288 A125225 A092903

Adjacent sequences:  A319793 A319794 A319795 * A319797 A319798 A319799

KEYWORD

nonn

AUTHOR

Omar E. Pol, Sep 28 2018

STATUS

approved

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Last modified January 24 13:24 EST 2020. Contains 331193 sequences. (Running on oeis4.)