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A066133
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In base 2, twelve 'Reverse and Add' steps are needed to reach a palindrome.
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1
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1027, 1139, 1181, 1229, 1433, 1481, 1537, 1649, 1951, 1983, 1999, 2031, 2051, 3073, 3103, 3215, 3351, 3463, 3611, 3639, 3671, 3723, 3751, 3783, 3839, 3859, 3971, 4087, 4103, 4121, 4141, 4187, 4237, 4269, 4327, 4331, 4333, 4361, 4427, 4603, 4625, 4645
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OFFSET
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1,1
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COMMENTS
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The analogue of A065217 in base 2. The number of steps starts at 0, so palindromes (cf. A006995) are excluded.
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LINKS
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Harry J. Smith, Table of n, a(n) for n=1,...,1000
Index entries for sequences related to Reverse and Add!
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PROG
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(PARI) Rev(x)= { local(d, r=0); while (x>0, d=x%10; x\=10; r=r*10 + d); return(r) } digitsIn(x)= { local(d); if (x==0, return(1)); d=1 + log(x)\log(10); if (10^d == x, d++, if (10^(d-1) > x, d--)); return(d) } Palin(x)= { local(d, e, f, i, t, y); if (x==0, return(1)); y=x; d=digitsIn(x); t=10^(d - 1); for (i=1, d\2, f=y-10*(y\10); y\=10; e=x\t; x-=t*e; t/=10; if (e!=f, return(0)) ); return(1) } baseE(x, b)= { local(d, e=0, f=1); while (x>0, d=x-b*(x\b); x\=b; e+=d*f; f*=10); return(e) } baseI(x, b)= { local(d, e=0, f=1); while (x>0, d=x-10*(x\10); x\=10; e+=d*f; f*=b); return(e) } calcB(p)= { local(b, r); b=baseE(p, 2); r=Rev(b); d=baseI(r, 2) + p; b=baseE(d, 2); return(b); } { n=0; for (m=1, 10^9, d=m; t=1; b=baseE(d, 2); for (i=1, 12, if (Palin(b), t=0; break); b=calcB(d)); if (t && Palin(b), write("b066133.txt", n++, " ", m); if (n==1000, return)) ) } [From Harry J. Smith, Feb 01 2010]
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CROSSREFS
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A006995, A065217, A066122.
Sequence in context: A004607 A221008 A168153 * A119455 A168189 A045031
Adjacent sequences: A066130 A066131 A066132 * A066134 A066135 A066136
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KEYWORD
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base,nonn
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AUTHOR
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Klaus Brockhaus, Dec 08 2001
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EXTENSIONS
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OFFSET changed from 0,1 to 1,1 by Harry J. Smith, Feb 01 2010
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STATUS
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approved
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