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Search: id:A070742
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| A070742 |
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a(n) = index of the (presumably) last palindrome in the 'Reverse and Add' trajectory of n, or -1 if this number is not finite, or 0 if no palindrome exists. |
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+0
17
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| 18, 17, 32, 16, 36, 31, 30, 15, 23, 35, 34, 30, 33, 29, 29, 14, 32, 22, 28, 34, 30, 33, 29, 29, 14, 32, 22, 28, 27, 30, 33, 29, 29, 14, 32, 22, 28, 27, 28, 33, 29, 29, 14, 32, 22, 28, 27, 28, 26, 29, 29, 14, 32, 22, 28, 27, 28, 26, 13, 29, 14, 32, 22, 28, 27, 28, 26, 13, 27
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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The computation of a trajectory was stopped, when within 1000 steps no further palindrome appeared. - A033665(n) + 1 is the index of the first palindrome in the 'Reverse and Add' trajectory of n.
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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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6, 33, 66, 363, 4884, 8836886388, 47337877873374 are the seven palindromes in the trajectory of 6 and the next 1000 steps do not lead to another palindrome; 47337877873374 is the 31st term in the trajectory, so a(6) = 31.
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PROGRAM
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(ARIBAS) var st, nst: string; end; for k := 1 to 74 do n := k; j := 1; x := 0; c := 0; while c < 1000 do st := itoa(n); nst := ""; for i := 0 to length(st) - 1 do nst := concat(st[i], nst); end; rev := atoi(nst); if n = rev then c := 0; x := j; end; inc(c); n := n + rev; inc(j); end; write(x, ", " ); end;
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CROSSREFS
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Cf. A033665, A065001, A070743, A070744.
Sequence in context: A022974 A023460 A029926 this_sequence A010857 A158910 A040307
Adjacent sequences: A070739 A070740 A070741 this_sequence A070743 A070744 A070745
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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), May 03 2002
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