A289283 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 5. The digit 0 is not allowed.

1, 4, 11, 41, 42, 3, 2, 31, 43, 21, 44, 12, 32, 33, 22, 34, 13, 23, 24, 14, 15

Offset

1,2

Comments

The number of terms of this finite sequence is the fifth central polygonal number, n = 21.

Links

Table of n, a(n) for n=1..21.

Mathematica

Module[{a = {1}, k}, TimeConstrained[Do[k = 2; While[Or[MemberQ[a, k], MemberQ[IntegerDigits@ k, 0], # != 5] &[Mod[a[[n - 1]], 10] + First@ IntegerDigits@ k], k++]; AppendTo[a, k], {n, 2, 24}], 2]; a] (* Michael De Vlieger, Jul 14 2017 *)

Crossrefs

Cf. A002061

Sequence in context: A077236 A327025 A228190 * A152532 A343548 A121096

Adjacent sequences: A289280 A289281 A289282 * A289284 A289285 A289286

Keyword

nonn,base,fini,full

Author

Enrique Navarrete, Jul 01 2017

Status

approved