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A163643 a(0)=1. For n >= 1, a(n) is the smallest composite integer that is > a(n-1) and that is coprime to n. 4
1, 4, 9, 10, 15, 16, 25, 26, 27, 28, 33, 34, 35, 36, 39, 44, 45, 46, 49, 50, 51, 52, 57, 58, 65, 66, 69, 70, 75, 76, 77, 78, 81, 82, 87, 88, 91, 92, 93, 94, 99, 100, 115, 116, 117, 118, 119, 120, 121, 122, 123, 124, 125, 126, 133, 134, 135, 136, 141, 142, 143, 144, 145 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Michael De Vlieger, Table of n, a(n) for n = 0..10000

MAPLE

A163643 := proc(n) if n = 0 then 1; else for a from procname(n-1)+1 do if not isprime(a) then if gcd(a, n) = 1 then return a; end if; end if; end do: end if; end proc: seq(A163643(n), n=0..100) ; # R. J. Mathar, Oct 09 2010

MATHEMATICA

a = {4}; Do[k = a[[n]] + 1; While[Nand[CompositeQ@ k, ! MemberQ[a, k], CoprimeQ[k, n + 1]], k++]; AppendTo[a, k], {n, 61}]; {1}~Join~a (* Michael De Vlieger, Jul 23 2017 *)

CROSSREFS

Cf. A051884, A139558, A163642.

Sequence in context: A157908 A064973 A133764 * A139558 A219556 A110602

Adjacent sequences:  A163640 A163641 A163642 * A163644 A163645 A163646

KEYWORD

nonn,easy

AUTHOR

Leroy Quet, Aug 02 2009

EXTENSIONS

More terms from R. J. Mathar, Oct 09 2010

STATUS

approved

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Last modified October 23 15:50 EDT 2021. Contains 348214 sequences. (Running on oeis4.)