A307807 Number of palindromic nonagonal numbers with exactly n digits.

3, 0, 3, 1, 2, 0, 2, 2, 5, 2, 1, 2, 0, 0, 0, 0, 1, 2, 3, 0, 1, 1

Offset

1,1

Comments

Number of terms in A082723 with exactly n digits.

Links

Table of n, a(n) for n=1..22.

G. J. Simmons, Palindromic powers, J. Rec. Math., 3 (No. 2, 1970), 93-98. [Annotated scanned copy] See page 95.

Example

There are only three 3 digit nonagonal numbers that are palindromic, 111, 474 and 969.  Thus, a(3)=3.

Mathematica

A082723 = {0, 1, 9, 111, 474, 969, 6666, 18981, 67276, 4411144, 6964696, 15444451, 57966975, 448707844, 460595064, 579696975, 931929139, 994040499, 1227667221, 9698998969, 61556965516, 664248842466, 699030030996, 99451743334715499, 428987160061789824, 950178723327871059, 1757445628265447571, 4404972454542794044, 9433971680861793349, 499583536595635385994, 1637992008558002997361, 19874891310701319847891}; Table[Length[Select[A082723, IntegerLength[#] == n || (n == 1 && # == 0) &]], {n, 22}]

Crossrefs

Cf. A001106, A055560, A082722, A082733, A307801, A307802.

Sequence in context: A336118 A342639 A300904 * A350849 A318504 A343877

Adjacent sequences: A307804 A307805 A307806 * A307808 A307809 A307810

Keyword

nonn,base,more

Author

Robert Price, Apr 29 2019

Status

approved