A289283 - OEIS

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

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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