A334320 Number of even integers in base n with exactly two distinct digits.

0, 0, 1, 1, 5, 6, 13, 15, 25, 28, 41, 45, 61, 66, 85, 91, 113, 120, 145, 153, 181, 190, 221, 231, 265, 276, 313, 325, 365, 378, 421, 435, 481, 496, 545, 561, 613, 630, 685, 703, 761, 780, 841, 861, 925, 946, 1013, 1035, 1105, 1128, 1201, 1225, 1301, 1326, 1405

Offset

0,5

Links

Alois P. Heinz, Table of n, a(n) for n = 0..10000

Index entries for linear recurrences with constant coefficients, signature (1,2,-2,-1,1).

Formula

G.f.: -(x^3+2*x^2+1)*x^2/((x+1)^2*(x-1)^3).

a(n) = A334318(n,2).

Example

a(4) = 5: 10, 12, 20, 30, 32 (written in base 4).
a(7) = 15: 13, 15, 20, 24, 26, 31, 35, 40, 42, 46, 51, 53, 60, 62, 64 (written in base 7).

Crossrefs

Column k=2 of A334318.

Sequence in context: A344221 A348155 A047436 * A061437 A067245 A059176

Adjacent sequences: A334317 A334318 A334319 * A334321 A334322 A334323

Keyword

nonn,easy

Author

Alois P. Heinz, Apr 22 2020

Status

approved