A073258 Numbers n such that gcd(c(n),n) = gcd(A002808(n),n) = A064814(n)=1 where c(n) is the n-th composite number.

1, 3, 4, 8, 9, 11, 13, 17, 19, 23, 25, 27, 29, 31, 33, 35, 37, 38, 39, 40, 41, 43, 44, 45, 46, 47, 49, 53, 57, 58, 59, 61, 66, 67, 68, 69, 71, 73, 79, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 94, 95, 97, 100, 101, 103, 106, 107, 108, 109, 111, 113, 115, 116, 117, 118, 119

Offset

1,2

Links

Table of n, a(n) for n=1..66.

Example

n=256: composite(256) = 323 = 17*19, gcd(323,256)=1, so 256 is a term.

Mathematica

c[x_] := FixedPoint[x+PrimePi[ # ]+1&, x]; t=Table[0, {256}]; s=0; k=0; Do[s=GCD[c[n], n]; If[Equal[s, 1], k=k+1; t[[k]]=n; Print[{k, n}]], {n, 1, 256}] t

Prog

(PARI) lista(nn) = {my(n=0, list=List()); forcomposite (c=1, nn, n++; if (gcd(n, c) == 1, listput(list, c))); Vec(list); } \\ Michel Marcus, Jul 19 2020

Crossrefs

Cf. A064814, A002808, A073257.

Sequence in context: A050003 A002156 A285033 * A170954 A286750 A359376

Adjacent sequences: A073255 A073256 A073257 * A073259 A073260 A073261

Keyword

nonn

Author

Labos Elemer, Jul 22 2002

Status

approved