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Search: id:A119460
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| A119460 |
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Composition of function F = x/(1-x) from functions of the form [x + a(n)*x^n]: F = a(1)*x o x+a(2)*x^2 o x+a(3)*x^3 o ... o x+a(n)*x^n o ... |
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+0
5
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| 1, 1, 1, -1, 3, -3, 6, -15, 58, -64, 198, -476, 1179, -2907, 8377, -19917, 69243, -131621, 379716, -995100, 2878526, -7230486, 21469716, -54741166, 156719748, -417925683, 1220839292, -3221204589, 9501389898, -25010664810, 73038583431, -197176327311, 595340630241
(list; graph; listen)
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OFFSET
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1,5
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EXAMPLE
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Iterated compositions of [x + a(n)*x^n] forms F = x/(1-x):
x/(1-x) = 1x o x+1x^2 o x+1x^3 o x-1x^4 o x+3x^5 o x-3x^6 o x+6x^7 o x-15x^8 o x+58x^9 o x-64x^10 o x+198x^11 o x-476x^12 o...
The compositions get closer to F = x/(1-x) at each iteration:
(1) 1*x = x;
(2) 1*x o x+x^2 = x + x^2;
(3) 1*x o x+x^2 o x+1x^3 = x + x^2 + x^3 + 2*x^4 + x^6;
(4) 1*x o x+x^2 o x+1x^3 o x-1x^4 =
x + x^2 + x^3 + x^4 - 2*x^5 - 2*x^6 - 8*x^7 + x^8 - 3*x^9 +...
(5) 1*x o x+x^2 o x+1x^3 o x-1x^4 o x+3x^5 =
x + x^2 + x^3 + x^4 + x^5 + 4*x^6 + x^7 + 13*x^8 - 33*x^9 +...
(6) 1*x o x+x^2 o x+1x^3 o x-1x^4 o x+3x^5 o x-3x^6 =
x + x^2 + x^3 + x^4 + x^5 + x^6 - 5*x^7 + 4*x^8 - 45*x^9 +...
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PROGRAM
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(PARI) {a(n)=local(F=x/(1-x+x*O(x^n)), G=x+x*O(x^n)); if(n<1, 0, if(n==1, polcoeff(F, 1), for(k=2, n, c=polcoeff(F/a(1), k)-polcoeff(G, k); G=subst(G, x, x+c*x^k); ); return(c)))}
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CROSSREFS
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Cf. A119459 (decomposition of x/(1-x)).
Sequence in context: A143418 A092370 A006807 this_sequence A095356 A123104 A038076
Adjacent sequences: A119457 A119458 A119459 this_sequence A119461 A119462 A119463
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KEYWORD
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sign
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AUTHOR
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Paul D. Hanna (pauldhanna(AT)juno.com), May 20 2006
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