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A107601
Column 6 of array illustrated in A089574 and related to A034261.
11
7, 71, 350, 1204, 3329, 7936, 16981, 33452, 61719, 107953, 180620, 291056, 454129, 688994, 1019947, 1477384, 2098871, 2930331, 4027354, 5456636, 7297553, 9643876, 12605633, 16311124, 20909095, 26571077, 33493896, 41902360, 52052129
OFFSET
0,1
COMMENTS
Column six is associated with the following partitions: 66, 552, 443, 4422, 3332, 33222 and 222222.
FORMULA
a(n) = A107601(10+n,5+n) = n*(1384+4683*n^2+2142*n+2*n^6+651*n^4+63*n^5+2835*n^3)/1680. a(n)= +8*a(n-1) -28*a(n-2) +56*a(n-3) -70*a(n-4) +56*a(n-5) -28*a(n-6) +8*a(n-7) -a(n-8). G.f.: x*(7+15*x-22*x^2+11*x^4-6*x^5+x^6)/(x-1)^8. [From R. J. Mathar, Jun 26 2010]
EXAMPLE
a(1) = 7 because there are 3 permutations of 443 and 4 permutations of 3332.
a(2) = 71 because there are 1 + 3 + 18 + 6 + 32 + 10 + 1 permutations of the associated partitions.
CROSSREFS
Cf. A107600.
Sequence in context: A069619 A137443 A362106 * A175863 A196742 A196900
KEYWORD
nonn
AUTHOR
Alford Arnold, May 27 2005
EXTENSIONS
Extended beyond a(5) by R. J. Mathar, Jun 26 2010
STATUS
approved