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0, 1, 3, 5, 13, 21, 28, 53, 85, 113, 213, 227, 341, 453, 853, 909, 1365, 1813, 1820, 3413, 3637, 5461, 7253, 7281, 13653, 14549, 14563, 21845, 29013, 29125, 54613, 58197, 58253, 87381
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OFFSET
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1,3
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COMMENTS
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Conjecture: sequence consists of an infinite number of subsequences S(m,0) = A172241(n) = (1/18)[8^n-(-1)^n-9], m>0, S(m,n+1) = 4*S(m,n)+1. The first subsequences
S(1,n) = A002450(n) = (4^n-1)/3 = = 0,1,5,21,85...,
S(2,n) = A072197(n) = (10*4^n-1)/3 = 3,13,53,213...,
S(3,n) = (85*4^n-1)/3 = 28,113,453...,
S(4,n) = (682*4^n-1)/3 = 227,909,3637..., and generally,
S(m,n) = [(3*A172241(m)+1)*4^n-1]/3.
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LINKS
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PROG
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(PARI) for(n=1, 300000, o=3*n/2^valuation(n, 2)+1; b=ispower(o); if(b&&b%2==0&&round(sqrtn(o, b/2))==4&&(n-1)%3==0, print1((n-1)/3, ", ")))
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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