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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.

LINKS

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

J. Alman, C. Lian, and B. Tran, Circular Planar Electrical Networks: Posets and Positivity, 2013.

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 26 23:01 EDT 2020. Contains 338033 sequences. (Running on oeis4.)