The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A194716 Number of n-ary words beginning with the first character of the alphabet, that can be built by inserting four doublets into the initially empty word. 2
 0, 1, 35, 181, 523, 1145, 2131, 3565, 5531, 8113, 11395, 15461, 20395, 26281, 33203, 41245, 50491, 61025, 72931, 86293, 101195, 117721, 135955, 155981, 177883, 201745, 227651, 255685, 285931, 318473, 353395, 390781, 430715, 473281, 518563, 566645, 617611 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 LINKS Alois P. Heinz, Table of n, a(n) for n = 0..1000 FORMULA G.f.: x*(1+31*x+47*x^2+5*x^3) / (x-1)^4. a(0) = 0, a(n) = 1+(6+(14+14*(n-1))*(n-1))*(n-1) for n>0. EXAMPLE a(2) = 35: aaaaaaaa, aaaaaabb, aaaaabba, aaaabaab, aaaabbaa, aaaabbbb, aaabaaba, aaabbaaa, aaabbabb, aaabbbba, aabaaaab, aabaabaa, aabaabbb, aababbab, aabbaaaa, aabbaabb, aabbabba, aabbbaab, aabbbbaa, aabbbbbb, abaaaaba, abaabaaa, abaababb, abaabbba, ababbaba, abbaaaaa, abbaaabb, abbaabba, abbabaab, abbabbaa, abbabbbb, abbbaaba, abbbbaaa, abbbbabb, abbbbbba (with 2-ary alphabet {a,b}). MAPLE a:= n-> `if`(n=0, 0, (x-> 1+(6+(14+14*x)*x)*x)(n-1)): seq(a(n), n=0..40); CROSSREFS Row n=4 of A183134. Sequence in context: A319042 A033851 A219825 * A220047 A101954 A220201 Adjacent sequences:  A194713 A194714 A194715 * A194717 A194718 A194719 KEYWORD nonn AUTHOR Alois P. Heinz, Sep 02 2011 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified October 30 05:44 EDT 2020. Contains 338077 sequences. (Running on oeis4.)