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0, 1, 2, 7, 20, 61, 180, 543, 1622, 4873, 14598, 43815, 131384, 394213, 1182456, 3547551, 10642110, 31926873, 95778990, 287338599, 862010924, 2586037645, 7758098316, 23274309567, 69822884886, 209468698473, 628405963974
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,3
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COMMENTS
| First differences of A102877, divided by 2.
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MATHEMATICA
| a[0] := 1; a[1] := 1; a[n_] := If[EvenQ[n], 3*a[n - 1], 3*a[n - 1] - 2*a[(n - 3)/2]]; Table[(a[i + 1] - a[i])/2, {i, 1, 50}] - Stefan Steinerberger (stefan.steinerberger(AT)gmail.com), May 22 2007
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PROG
| (PARI) {m=27; v=vector(m+1); v[1]=1; v[2]=1; for(n=2, m, k=3*v[n]; if(n%2==1, k=k-2*v[(n-1)/2]); v[n+1]=k); w=vector(m, n, (v[n+1]-v[n])/2); print(w)} /* Klaus Brockhaus, May 20 2007 */
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CROSSREFS
| Cf. A102877.
Sequence in context: A025180 A201967 A116950 * A116408 A014983 A015518
Adjacent sequences: A111014 A111015 A111016 * A111018 A111019 A111020
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KEYWORD
| nonn
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AUTHOR
| Paul Curtz (bpcrtz(AT)free.fr), May 17 2007
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EXTENSIONS
| Edited and extended by Klaus Brockhaus (klaus-brockhaus(AT)t-online.de) and Stefan Steinerberger (stefan.steinerberger(AT)gmail.com), May 20 2007
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