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 A073969 Number of strings of length n over Z_5 with trace 1 and subtrace 3. 7
 0, 2, 6, 30, 125, 650, 3150, 15750, 78000, 390625, 1952500, 9768750, 48831250, 244156250, 1220703125, 6103593750, 30517656250, 152588281250, 762939062500, 3814697265625, 19073484375000, 95367441406250, 476837167968750, 2384185839843750, 11920928955078125 (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 2 and subtrace 2, trace 3 and subtrace 2, or trace 4 and subtrace 3. Same as the number of strings of length n over GF(5) with: trace 1 and subtrace 3, trace 2 and subtrace 2, trace 3 and subtrace 2, or trace 4 and subtrace 3. LINKS Max Alekseyev, PARI/GP scripts for miscellaneous math problems 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.: -x^2*(25*x^5-50*x^4+65*x^3-40*x^2+14*x-2) / ((5*x-1)*(5*x^2-1)*(25*x^4-25*x^3+15*x^2-5*x+1)). - Colin Barker, Nov 26 2014 EXAMPLE a(2;3,2)=2 since the two 5-ary strings of trace 3, subtrace 2 and length 2 are { 12, 21 }. CROSSREFS Cf. A073963, A073964, A073965, A073966, A073967, A073968, A073970. Sequence in context: A036752 A065563 A035105 * A295863 A224530 A120950 Adjacent sequences:  A073966 A073967 A073968 * A073970 A073971 A073972 KEYWORD easy,nonn AUTHOR Frank Ruskey and 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 12:46 EDT 2022. Contains 356212 sequences. (Running on oeis4.)