A264406 - OEIS

A264406

Smallest palindrome of each distinct decimal type (A002113) in increasing order.

1, 11, 101, 111, 1001, 1111, 10001, 10101, 10201, 11011, 11111, 100001, 101101, 102201, 110011, 111111, 1000001, 1001001, 1002001, 1010101, 1011101, 1012101, 1020201, 1021201, 1022201, 1023201, 1100011, 1101011, 1102011, 1110111, 1111111, 10000001, 10011001, 10022001, 10100101, 10111101, 10122101, 10200201, 10211201, 10222201, 10233201, 11000011, 11011011, 11022011, 11100111, 11111111

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OFFSET

1,2

COMMENTS

Only positive palindromes are considered.

The numbers N(n) of distinct types of n-digit palindromes, for n=1,2,..., are 1,1,2,2,5,5,15,15,... (A164904, n>=1). It is easy to see that N(2*n-1)=N(2*n), n>=1.

LINKS

Peter J. C. Moses, Table of n, a(n) for n = 1..6450

EXAMPLE

The type corresponding to the term 1021201 has the form XYZXZYX, where X,Y,Z are distinct decimal digits, X>0.

CROSSREFS

Cf. A002113, A164904.

Sequence in context: A193415 A263609 A333415 * A057148 A076289 A350346

Adjacent sequences: A264403 A264404 A264405 * A264407 A264408 A264409

KEYWORD

nonn,base

AUTHOR

Vladimir Shevelev, Dec 10 2015

EXTENSIONS

Two missed terms were found by Peter J. C. Moses, Jan 07 2016

STATUS

approved