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Search: id:A077441
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| A077441 |
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In base 4, smallest number which requires n Reverse and Add! steps to reach a palindrome. |
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+0
2
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| 0, 4, 7, 26, 28, 127, 306, 348, 398, 301, 308, 203, 311, 783, 294, 350, 199, 296, 4268, 16595, 5326, 4253, 17399, 8235, 6189, 4270, 3107, 1270, 1532, 511, 67816, 65975, 24670, 12395, 4282, 3119, 28799, 16861, 18164, 66268, 45087, 71164, 309234
(list; graph; listen)
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OFFSET
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0,2
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COMMENT
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Base-4 analogue of A066058 (base 2) and A023109 (base 10).
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LINKS
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Index entries for sequences related to Reverse and Add!
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EXAMPLE
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7 is the smallest number which requires two steps to reach a base 4 palindrome (cf. A075685), so a(2) = 5; 7 (decimal) = 13 -> 13 + 31 = 110 -> 110 + 011 = 121 (palindrome) = 25 (decimal).
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PROGRAM
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(PARI) {m=46; v=[]; for(j=1, m+1, v=concat(v, -1)); mc=m+1; n=0; while(mc>0, a=-1; c=0; k=n; while(c<m+1, q=k; rev=0; while(q>0, d=divrem(q, 4); q=d[1]; rev=4*rev+d[2]); if(k==rev, a=c; c=m+1, c++; k=k+rev)); if(0<=a&&a<=m, if(v[a+1]<0, v[a+1]=n; mc--; print1([a, n]))); n++); print(); for(j=1, m+1, print1(v[j], ", "))}
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CROSSREFS
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Cf. A075685, A066058, A023109.
Sequence in context: A151348 A110413 A075686 this_sequence A076148 A146085 A061668
Adjacent sequences: A077438 A077439 A077440 this_sequence A077442 A077443 A077444
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KEYWORD
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base,nonn
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AUTHOR
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Klaus Brockhaus (klaus-brockhaus(AT)t-online.de), Nov 05 2002
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