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A132317
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a(n) = [x^(2^n)] Product_{i=0..n} (1 + x^(2^i) )^(2^(n-i)); equals column 1 of triangle A132318.
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2
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OFFSET
| 0,2
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COMMENTS
| Next term, a(8), has 126 digits.
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EXAMPLE
| a(0) = [x] (1+x) = 1;
a(1) = [x^2] (1+x)^2*(1+x^2) = 2;
a(2) = [x^4] (1+x)^4*(1+x^2)^2*(1+x^4) = 15;
a(3) = [x^8] (1+x)^8*(1+x^2)^4*(1+x^4)^2*(1+x^8) = 1024;
a(4) = [x^16] (1+x)^16*(1+x^2)^8*(1+x^4)^4*(1+x^8)^2*(1+x^16) = 7048181.
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PROG
| (PARI) {a(n)=polcoeff(prod(i=0, n, (1 + x^(2^i) +x*O(x^(2^n)))^(2^(n-i))), 2^n)}
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CROSSREFS
| Cf. A132318, A132316.
Sequence in context: A007542 A090604 A007467 * A068409 A096232 A193869
Adjacent sequences: A132314 A132315 A132316 * A132318 A132319 A132320
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KEYWORD
| nonn
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AUTHOR
| Paul D. Hanna (pauldhanna(AT)juno.com), Aug 19 2007
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