A028359 Two-bell analog of A028355.

1, 2, 12, 121, 212, 1212, 12121, 21212, 121212, 1212121, 2121212, 12121212, 121212121, 212121212, 1212121212, 12121212121, 21212121212, 121212121212, 1212121212121, 2121212121212, 12121212121212, 121212121212121, 212121212121212, 1212121212121212, 12121212121212121

Offset

1,2

Comments

Consider the infinite digits: 121212... . We can break this into a sequence of integers such that the sum of digits in the n-th value is n. - Seiichi Manyama, Oct 31 2018

Links

Seiichi Manyama, Table of n, a(n) for n = 1..1500

Formula

Conjectures from Chai Wah Wu, Apr 18 2024: (Start)

a(n) = 101*a(n-3) - 100*a(n-6) for n > 6.

G.f.: x*(10*x^4 + 20*x^3 + 12*x^2 + 2*x + 1)/(100*x^6 - 101*x^3 + 1). (End)

Crossrefs

Cf. A000034, A028355.

Sequence in context: A062080 A221279 A165300 * A034524 A051782 A048173

Adjacent sequences: A028356 A028357 A028358 * A028360 A028361 A028362

Keyword

nonn,base

Author

N. J. A. Sloane

Extensions

More terms from Seiichi Manyama, Oct 31 2018

Status

approved