A065983 Palindromes whose digit sum is 4.

4, 22, 121, 202, 1111, 2002, 10201, 11011, 20002, 101101, 110011, 200002, 1002001, 1010101, 1100011, 2000002, 10011001, 10100101, 11000011, 20000002, 100020001, 100101001, 101000101, 110000011, 200000002, 1000110001, 1001001001

Offset

1,1

Comments

There are ceiling(k/2) terms with k digits and so floor(n^2/4) terms with fewer than k digits. Writing the terms as a vertical column and then blanking zeros produces a narrow triangle with upward chevrons.

Links

Table of n, a(n) for n=1..27.

Crossrefs

Cf. A062397 and A066138 for digit sums of 2 and 3.

Sequence in context: A261193 A025569 A098834 * A236576 A375724 A185858

Adjacent sequences: A065980 A065981 A065982 * A065984 A065985 A065986

Keyword

base,nonn

Author

Henry Bottomley, Dec 10 2001

Status

approved