A289287 Starting with a(1) = 1, a(n) = smallest nonnegative integer not yet in the sequence such that the last digit of a(n-1) plus the first digit of a(n) is equal to 9. The digit 0 is not allowed.

1, 8, 11, 81, 82, 7, 2, 71, 83, 6, 3, 61, 84, 5, 4, 51, 85, 41, 86, 31, 87, 21, 88, 12, 72, 73, 62, 74, 52, 75, 42, 76, 32, 77, 22, 78, 13, 63, 64, 53, 65, 43, 66, 33, 67, 23, 68, 14, 54, 55, 44, 56, 34, 57, 24, 58, 15, 45, 46, 35, 47, 25, 48, 16, 36, 37, 26, 38, 17, 27, 28, 18, 19

Offset: 1

Author

Enrique Navarrete, Jul 01 2017

Keywords

• nonn
• base
• fini
• full

Comments

The number of terms of this finite sequence is the ninth central polygonal number, n = 73.

Crossrefs

Cf. A002061, A289283, A289284, A289285, A289286.

Programs

Mathematica

Module[{a = {1}, k, d = 9}, TimeConstrained[Do[k = 2; While[Or[MemberQ[a, k], MemberQ[IntegerDigits@ k, 0], # != d] &[Mod[a[[n - 1]], 10] + First@ IntegerDigits@ k], k++]; AppendTo[a, k], {n, 2, 100}], 2]; a] (* Michael De Vlieger, Jul 14 2017 *)