

A007985


Cogrowth function of a certain group.


1



2, 2, 6, 22, 58, 146, 414, 1206, 3410, 9634, 27670, 79926, 230666, 667058, 1936174, 5632662, 16408866, 47875650, 139908774, 409404630, 1199368026, 3517351890, 10325547582, 30339113718, 89217594738, 262561101282, 773248631222, 2278737199606
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OFFSET

1,1


REFERENCES

Stephen P Humphries, "Cogrowth of groups and the DedekindFrobenius group determinant", Mathematical Proceeding of the Cambridge Philosophical Society volume 121 Part 2 pages 193217 (1997).


LINKS



FORMULA

G.f. (x+1) * sqrt(1x) / sqrt((13*x) * (3*x^2+1)) [from Humphries].  Sean A. Irvine, Feb 26 2018


CROSSREFS



KEYWORD

nonn


AUTHOR



EXTENSIONS



STATUS

approved



