0,2

With a different offset, number of n-permutations (n=5) of 8 objects s, t, u, v, w, z, x, y with repetition allowed, containing exactly four (4)u's. Example: a(1)=35 because we have

uuuus, uuusu, uusuu, usuuu, suuuu,

uuuut, uuutu, uutuu, utuuu, tuuuu,

uuuuv, uuuvu, uuvuu, uvuuu, vuuuu,

uuuuw, uuuwu, uuwuu, uwuuu, wuuuu,

uuuuz, uuuzu, uuzuu, uzuuu, zuuuu,

uuuux, uuuxu, uuxuu, uxuuu, xuuuu,

uuuuy, uuuyu, uuyuu, uyuuu, yuuuu.

seq(binomial(n+4, 4)*7^n, n=0..20);

Adjacent sequences: A139638 A139639 A139640 this_sequence A139642 A139643 A139644

Sequence in context: A010987 A112504 A140405 this_sequence A028220 A028213 A028212

nonn

Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Jun 12 2008