A325323 Palindromes in base 10 that are not Brazilian.

1, 2, 3, 4, 5, 6, 9, 11, 101, 131, 151, 181, 191, 313, 353, 373, 383, 727, 787, 797, 919, 929, 10201, 10301, 10501, 10601, 11311, 11411, 12421, 12721, 12821, 13331, 13831, 13931, 14341, 14741, 15451, 15551, 16061, 16361, 16561, 16661, 17471, 17971, 18181, 18481, 19391, 19891, 19991

Offset: 1

Author

Bernard Schott, Apr 20 2019

Keywords

• nonn
• base

Comments

The terms >= 11 of this sequence are either prime palindromes which are not Brazilian, or square of primes (except 121).

Links

• Amiram Eldar, Table of n, a(n) for n = 1..1000

Crossrefs

Intersection of A002113 and A220570.

Complement of A325322 with respect to A002113.

Cf. A088882 (Palindromes not repdigits).

Programs

Mathematica

brazQ[n_] := Module[{b = 2, found = False}, While[b < n - 1 && Length @ Union[IntegerDigits[n, b]] > 1, b++]; b < n - 1]; Select[Range[20000], PalindromeQ[#] && !brazQ[#] &] (* Amiram Eldar, Apr 14 2021 *)

PARI

isb(n) = for(b=2, n-2, my(d=digits(n, b)); if(vecmin(d)==vecmax(d), return(1))); \\ A125134
isp(n) = my(d=digits(n)); d == Vecrev(d); \\ A002113
isok(n) = !isb(n) && isp(n); \\ Michel Marcus, Apr 22 2019