A128375 -id:A128375 - cp's OEIS frontend

A043044 Palindromes that start with 9.

9, 99, 909, 919, 929, 939, 949, 959, 969, 979, 989, 999, 9009, 9119, 9229, 9339, 9449, 9559, 9669, 9779, 9889, 9999, 90009, 90109, 90209, 90309, 90409, 90509, 90609, 90709, 90809, 90909, 91019, 91119, 91219, 91319, 91419, 91519, 91619, 91719, 91819, 91919

Offset: 1

Clark Kimberling

Subsequence of A002113 (palindromic numbers). Union of A128375 (palindromic primes starting with a digit 9) and A222729 (palindromic composite numbers starting with a digit 9). - Jaroslav Krizek, Mar 12 2013

Jaroslav Krizek, Table of n, a(n) for n = 1..2222

palQ[n_Integer, base_Integer] := Module[{idn = IntegerDigits[n, base]}, idn == Reverse[idn]]; Select[Range[0, 100000], IntegerDigits[#][[1]] == 9 && palQ[#, 10] &] (* T. D. Noe, Mar 12 2013 *)
Select[Range[100000],PalindromeQ[#]&&IntegerDigits[#][[1]]==9&] (* Harvey P. Dale, Oct 13 2022 *)
Join[{9},Table[Select[Flatten[Range[9*10^ex+9,10^(ex+1)-1,10]],PalindromeQ],{ex,4}]]//Flatten (* Harvey P. Dale, Apr 02 2025 *)

A222729 Palindromic composite numbers starting with a digit 9.

Original entry on oeis.org

9, 99, 909, 939, 949, 959, 969, 979, 989, 999, 9009, 9119, 9229, 9339, 9449, 9559, 9669, 9779, 9889, 9999, 90009, 90109, 90209, 90309, 90409, 90509, 90609, 90809, 90909, 91119, 91219, 91319, 91419, 91519, 91619, 91719, 91819, 91919, 92029, 92129, 92229, 92329

Offset: 1

Jaroslav Krizek, Mar 03 2013

Subsequence of A032350 (palindromic nonprime numbers) and A002113 (palindromic numbers). Complement of A128375 (palindromic primes starting with a digit 9) with respect to A043044 (palindromic numbers starting with a digit 9).

Jaroslav Krizek, Table of n, a(n) for n = 1..1050

Cf. A032350, A002113, A128375, A043044.

Select[Range[100000],PalindromeQ[#]&&CompositeQ[#]&&IntegerDigits[#][[1]] == 9&] (* Harvey P. Dale, Oct 09 2021 *)

A128374 Emirps starting and ending with composite digit 9.

Original entry on oeis.org

9029, 9209, 9349, 9439, 9479, 9679, 9749, 9769, 90019, 90059, 90089, 90149, 90199, 90499, 90679, 90749, 90989, 91009, 91129, 91199, 91229, 91249, 91459, 92119, 92189, 92219, 92369, 92459, 92479, 92489, 92639, 92779, 92789, 92899, 92959

Offset: 1

Lekraj Beedassy, Feb 27 2007

Cf. A006567, A128375.

Corrected and extended by Ray Chandler, Feb 28 2007

A128376 Palindromic primes with only composite digits (i.e.,4,6,8,9).

Original entry on oeis.org

94649, 94849, 94949, 96469, 98689, 9446449, 9686869, 9888889, 9889889, 9896989, 9989899, 944999449, 946666649, 946999649, 948898849, 964444469, 964989469, 966848669, 968646869, 968666869, 968868869, 968898869, 968999869, 986444689

Offset: 1

Lekraj Beedassy, Feb 27 2007

Subsequence of A128375.

Cf. A002385, A083185.

Select[Flatten[Table[FromDigits/@Tuples[{4,6,8,9},n],{n,9}]],PalindromeQ[ #] && PrimeQ[#]&] (* Harvey P. Dale, Dec 20 2018 *)

Corrected by Ray Chandler, Feb 28 2007

cp's OEIS Frontend

A043044 Palindromes that start with 9.

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A222729 Palindromic composite numbers starting with a digit 9.

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A128374 Emirps starting and ending with composite digit 9.

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A128376 Palindromic primes with only composite digits (i.e.,4,6,8,9).

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