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A133107 Number of Ferrers diagrams with a single strictly smaller Ferrers puncture with the same orientation removed from the top with half-perimeter=n. +0
2
1, 7, 32, 121, 410, 1294, 3888, 11273, 31826, 88041, 239734, 644758, 1717191, 4538129, 11919760, 31156313, 81125827, 210604604, 545462798, 1410226551, 3641097828, 9391872711, 24208902420, 62373915102, 160663604377 (list; graph; listen)
OFFSET

6,2

LINKS

Arvind Ayyer (ayyer(AT)physics.rutgers.edu), Sep 11 2007, Table of n, a(n) for n = 6..76

FORMULA

G.F.=x^2*(-1+3*x-x^2+(5*x^4-6*x^3+11*x^2-6*x+1+4*x^6-12*x^5)^(1/2))/(2*(x^2-3*x+1)*(1-2*x)^2)

EXAMPLE

The sequence starts with n=6 because the smallest such object whose cartoon is below has a perimeter of 12. (1 denotes cell inside the Ferrers diagram)

1 1

111

CROSSREFS

Cf. A057410, A057406, A133106.

Sequence in context: A126562 A001794 A140289 this_sequence A034360 A050148 A024093

Adjacent sequences: A133104 A133105 A133106 this_sequence A133108 A133109 A133110

KEYWORD

easy,nonn

AUTHOR

Arvind Ayyer (ayyer(AT)physics.rutgers.edu), Sep 11 2007

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Last modified August 19 23:53 EDT 2008. Contains 142930 sequences.


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