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A076131
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a(n) = 2^n*a(n-1) + 1, a(0) = 0.
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6
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0, 1, 5, 41, 657, 21025, 1345601, 172236929, 44092653825, 22575438758401, 23117249288602625, 47344126543058176001, 193921542320366288900097, 1588605274688440638669594625, 26027708820495411423962638336001, 852875962629993641540407732994080769
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OFFSET
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0,3
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COMMENTS
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Base-2 expansion is same as base 10 expansion of A076127.
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LINKS
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FORMULA
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a(n) = floor(c*2^((n+1)*(n+2)/2)) where c = sum(k>=1, 1/2^A000217(k))=0.6416325... - Benoit Cloitre, Nov 01 2002
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MATHEMATICA
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a[0] = 0; a[n_] := 2^n a[n - 1] + 1; Table[ a[n], {n, 0, 13}]
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PROG
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(PARI) a(n)=if(n<0, 0, subst(Polrev(Vec(sum(k=1, n, x^(k*(k+1)/2)))), x, 2))
(PARI) a(n)=if(n<1, 0, 1+a(n-1)*2^n)
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CROSSREFS
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KEYWORD
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easy,nonn,base
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AUTHOR
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Kyle Hunter (hunterk(AT)raytheon.com), Oct 31 2002
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EXTENSIONS
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STATUS
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approved
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