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A073964 Number of strings of length n over Z_5 with trace 0 and subtrace 1. 7
0, 2, 6, 20, 100, 600, 3150, 15750, 78000, 390000, 1952500, 9768750, 48831250, 244125000, 1220625000, 6103437500, 30517656250, 152588281250, 762939062500, 3814695312500, 19073484375000, 95367441406250, 476837167968750, 2384185742187500, 11920928710937500 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Same as the number of strings of length n over Z_5 with trace 0 and subtrace 4.

Same as the number of strings of length n over GF(5) with trace 0 and subtrace 1.

Same as the number of strings of length n over GF(5) with trace 0 and subtrace 4.

LINKS

Table of n, a(n) for n=1..25.

Max Alekseyev, PARI/GP scripts for miscellaneous math problems

F. Ruskey, Strings over Z_5 with given trace and subtrace

F. Ruskey, Strings over GF(5) with given trace and subtrace

FORMULA

a(n; t, s) = a(n-1; t, s) + a(n-1; t+4, s+4t+1) + a(n-1; t+3, s+3t+4) + a(n-1; t+2, s+2t+4) + a(n-1; t+1, s+t+1).

Empirical g.f.: 2*x^2*(50*x^5-50*x^4+5*x^3+15*x^2-7*x+1) / ((5*x-1)*(5*x^2-1)*(25*x^4-25*x^3+15*x^2-5*x+1)). - Colin Barker, Apr 03 2015

CROSSREFS

Cf. A073963, A073965, A073966, A073967, A073968, A073969, A073970.

Sequence in context: A026991 A049379 A003094 * A079457 A321911 A079455

Adjacent sequences:  A073961 A073962 A073963 * A073965 A073966 A073967

KEYWORD

easy,nonn

AUTHOR

Frank Ruskey, Nate Kube, Aug 15 2002

EXTENSIONS

Terms a(11) onward from Max Alekseyev, Apr 09 2013

STATUS

approved

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Last modified August 18 11:47 EDT 2022. Contains 356212 sequences. (Running on oeis4.)