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A056413
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Number of step cyclic shifted sequences using a maximum of five different symbols.
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7
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5, 15, 35, 120, 201, 1505, 2015, 14070, 37085, 246753, 445515, 5205790, 7832185, 72703645, 254689657, 1196213445, 2805046965, 35322811755, 55770979195, 596439735024, 1892294578755, 10837223014665, 23559159229935, 310484619147940, 596046508875701, 4776013513099405, 15330413466776835, 110874578286500410
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OFFSET
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1,1
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COMMENTS
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See A056371 for an explanation of step shifts. Under step cyclic shifts, abcde, bdace, bcdea, cdeab and daceb etc. are equivalent.
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REFERENCES
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M. R. Nester (1999). Mathematical investigations of some plant interaction designs. PhD Thesis. University of Queensland, Brisbane, Australia. [See A056391 for pdf file of Chap. 2]
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LINKS
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FORMULA
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Refer to Titsworth or slight "simplification" in Nester.
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MATHEMATICA
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M[j_, L_] := Module[{m = 1}, While[Sum[ j^i, {i, 0, m - 1}] ~Mod~ L != 0, m++]; m]; c[j_, t_, n_] := Sum[ 1/M[j, n / GCD[n, u*(j - 1) + t] ], {u, 0, n - 1} ]; CB[n_, k_] = If [n == 1, k, 1/(n*EulerPhi[n]) * Sum[ If[1 == GCD[n, j], k^c[j, t, n], 0] , {t, 0, n-1}, {j, 1, n-1}]]; Table[ Print[ cb = CB[n, 5]]; cb, {n, 1, 28}] (* Jean-François Alcover, Dec 04 2015, after Joerg Arndt *)
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PROG
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(PARI) \\ see p.3 of the Dokovic et al. reference
M(j, L)={my(m=1); while ( sum(i=0, m-1, j^i) % L != 0, m+=1 ); m; }
c(j, t, n)=sum(u=0, n-1, 1/M(j, n / gcd(n, u*(j-1)+t) ) );
CB(n, k)=if (n==1, k, 1/(n*eulerphi(n)) * sum(t=0, n-1, sum(j=1, n-1, if(1==gcd(n, j), k^c(j, t, n), 0) ) ) );
for(n=1, 66, print1(CB(n, 5), ", "));
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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