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Search: id:A128984
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| A128984 |
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Degree of the special subgraph of Cayley graph constracted using the special (123)-avoiding and (132)-avoiding permutation patterns as generators. |
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3
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| 2, 4, 6, 10, 12, 16, 18, 22, 28, 30, 36, 40, 42, 46, 50, 52, 56, 58, 60, 66, 70, 72, 76, 78, 82, 86, 88, 90, 96, 100, 102, 106, 110, 112, 116, 118, 122, 128, 130, 136, 140, 142, 146, 148, 150, 156, 160, 166, 170, 172, 178, 180, 182, 186, 190, 192, 196, 198, 200, 202
(list; graph; listen)
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OFFSET
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3,1
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COMMENT
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This sequence is constructed using a special veriety of subgraphs of Cayley graphs in order for a study of the degree/diameter problem.
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REFERENCES
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Ibrahim A.A. and Audu M.S.(2005) Some Group Theoretic Properties of Certain Class of (123) and (132)-Avoiding Patterns of Numbers: An Enumeration Scheme: An enumeration Scheme, African Journal of Natural Sciences, Vol. 8:79-84
Ibrahim A.A. (2006) A Counting Scheme And Some Algebraic Properties of A Class of Special Permutation Patterns. (in preparation)
Ibrahim A.A. (2005) On the Combinatorics of Succession In A 5-element Sample Abacus Journal of Mathematical Association of Nigeria Vol. 32, No. 2B:410-415
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FORMULA
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f(n) = Pn-1; where Pn denotes the n-th prime number, n>2
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EXAMPLE
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Example: when n=3, f(3)=P3-1=3-1 since 3is the third prime number in the list of primes. whenn n=4, f(4)=5-1=4, since 5 is the fifth prime number in the list of primes.
Recursion relation:f(0)=2, f(2)=4, f(3)=6, f(4)=12, f(5)=f(1)+f(2)+f(3)+f(4)/f(0), f(n)=f(n-1)+f(n-2)+f(n-3)+f(n-4)-f(n-5)/f(0)-f(n-5), n>5 and provided the difference between consecutive numbers (before and at the start of the addition) does not exceed four digits. If however, this difference (m-(m-1)<=4 the f(n)=f(n-1)+f(n-2)+f(n-3)+f(n-4)/f(0)-f(n-4).
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CROSSREFS
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Cf. A123642, A119626, A128929.
Sequence in context: A082417 A161842 A085477 this_sequence A075728 A146886 A006093
Adjacent sequences: A128981 A128982 A128983 this_sequence A128985 A128986 A128987
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KEYWORD
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nonn,uned
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AUTHOR
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Aminu Alhaji Ibrahim (aminualhaji(AT)yahoo.co.uk), Apr 30 2007
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