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A232967 Irregular triangle read by rows: row n lists the rank sizes of the "electrical" poset EP_n of circular planar graphs with n boundary vertices. 1
1, 1, 1, 1, 3, 3, 1, 1, 6, 14, 16, 10, 4, 1, 1, 10, 40, 85, 110, 97, 65, 35, 15, 5, 1, 1, 15, 90, 295, 609, 873, 948, 840, 636, 421, 246, 126, 56, 21, 6, 1, 1, 21, 175, 805, 2366, 4872, 7567, 9459, 10031, 9359, 7861, 6027, 4249, 2765, 1661, 917, 462, 210, 84, 28, 7, 1, 1, 28, 308, 1876, 7350, 20272, 42090, 69620, 96334, 115980, 125044, 123176, 112380, 95836, 76868, 58220, 41734, 28344, 18236, 11096, 6364, 3424, 1716, 792, 330, 120, 36, 8, 1 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,5

COMMENTS

More than the usual number of terms are given, since the connection with A111088 seems rather mysterious.

REFERENCES

J. Alman, C. Lian, B. Tran, Circular Planar Electrical Networks: Posets and Positivity, 2013; http://www.math.umn.edu/~reiner/REU/AlmanLianTran2013.pdf

LINKS

Table of n, a(n) for n=1..92.

EXAMPLE

Triangle begins:

1,

1, 1,

1, 3, 3, 1,

1, 6, 14, 16, 10, 4, 1,

1, 10, 40, 85, 110, 97, 65, 35, 15, 5, 1,,

1, 15, 90, 295, 609, 873, 948, 840, 636, 421, 246, 126, 56, 21, 6, 1,

1, 21, 175, 805, 2366, 4872, 7567, 9459, 10031, 9359, 7861, 6027, 4249, 2765, 1661, 917, 462, 210, 84, 28, 7, 1,

1, 28, 308, 1876, 7350, 20272, 42090, 69620, 96334, 115980, 125044, 123176, 112380, 95836, 76868, 58220, 41734, 28344, 18236, 11096, 6364, 3424, 1716, 792, 330, 120, 36, 8, 1,

...

CROSSREFS

Row sums give A111088.

Sequence in context: A244500 A300695 A296186 * A144163 A080858 A144228

Adjacent sequences:  A232964 A232965 A232966 * A232968 A232969 A232970

KEYWORD

nonn,tabf

AUTHOR

N. J. A. Sloane, Dec 04 2013

STATUS

approved

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Last modified October 15 01:40 EDT 2019. Contains 328025 sequences. (Running on oeis4.)