0,2

With a different offset, number of n-permutations (n>=7) of 7 objects: s, t, u, v, z, x, y with repetition allowed, containing exactly seven (7) u's.

If n=7 then a(0)= 1 because we have uuuuuuu

a(1)=48 because we have

uuuuuuus, uuuuuuut, uuuuuuuv, uuuuuuuz, uuuuuuux, uuuuuuuy,

uuuuuusu, uuuuuutu, uuuuuuvu, uuuuuuzu, uuuuuuxu, uuuuuuyu,

uuuuusuu, uuuuutuu, uuuuuvuu, uuuuuzuu, uuuuuxuu, uuuuuyuu,

uuuusuuu, uuuutuuu, uuuuvuuu, uuuuzuuu, uuuuxuuu, uuuuyuuu,

uuusuuuu, uuutuuuu, uuuvuuuu, uuuzuuuu, uuuxuuuu, uuuyuuuu,

uusuuuuu, uutuuuuu, uuvuuuuu, uuzuuuuu, uuxuuuuu, uuyuuuuu,

usuuuuuu, utuuuuuu, uvuuuuuu, uzuuuuuu, uxuuuuuu, uyuuuuuu,

suuuuuuu, tuuuuuuu, vuuuuuuu, zuuuuuuu, xuuuuuuu, yuuuuuuu.

O.g.f.: 1/(1-6x)^8. [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Aug 08 2008]

seq(binomial(n+7, 7)*6^n, n=0..16);

Cf. A038255.

Sequence in context: A025233 A004425 A082558 this_sequence A004341 A089272 A004362

Adjacent sequences: A141404 A141405 A141406 this_sequence A141408 A141409 A141410

nonn

Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Aug 04 2008