A289285 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 7. The digit 0 is not allowed.

1, 6, 11, 61, 62, 5, 2, 51, 63, 4, 3, 41, 64, 31, 65, 21, 66, 12, 52, 53, 42, 54, 32, 55, 22, 56, 13, 43, 44, 33, 45, 23, 46, 14, 34, 35, 24, 36, 15, 25, 26, 16, 17

Offset

1,2

Comments

The number of terms of this finite sequence is the seventh central polygonal number, n = 43.

Links

Table of n, a(n) for n=1..43.

Mathematica

Module[{a = {1}, k, d = 7}, 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 *)

Crossrefs

Cf. A002061, A289283, A289284.

Sequence in context: A177197 A177162 A152448 * A073219 A365496 A110445

Adjacent sequences: A289282 A289283 A289284 * A289286 A289287 A289288

Keyword

nonn,base,fini,full

Author

Enrique Navarrete, Jul 01 2017

Status

approved