A222729 Palindromic composite numbers starting with a digit 9.

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

Author

Jaroslav Krizek, Mar 03 2013

Keywords

• nonn
• base

Comments

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).

Links

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

Crossrefs

Cf. A032350, A002113, A128375, A043044.

Programs

Mathematica

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