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A248754
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Palindromes p=A002113(n) whose index n is also a palindrome and in addition a substring of p (strings in base 10).
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1
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11, 1111, 12221, 23332, 34443, 45554, 56665, 67776, 78887, 89998, 111111, 1222221, 2333332, 3444443, 4555554, 5666665, 6777776, 7888887, 8999998, 9101019, 11111111, 102020201, 112121211, 122222221, 132323231, 142424241, 152525251, 162626261, 172727271, 182828281
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OFFSET
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1,1
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COMMENTS
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This is a proper subsequence of A248753 (where the index does not need to be palindromic).
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LINKS
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EXAMPLE
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11 is a term because the eleventh palindrome is 11.
1111 is a member because it is the 111th palindrome.
12221 is in the sequence because the 222nd palindrome is 12221.
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MATHEMATICA
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(* first load 'nthPalindrome' from A002113 and then *) nPal[n_] := nthPalindrome[n - 1]; fQ[n_] := StringPosition[ ToString[ nPal[ nPal[ k]]], ToString[ nPal[ n]]] != {}; k = 2; lst = {}; While[k < 501, If[ fQ[k], AppendTo[lst, nPal[ nPal[ k]] ]]; k++]; lst
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CROSSREFS
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KEYWORD
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nonn,base,easy
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AUTHOR
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STATUS
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approved
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