A090094 a(n) is the smallest composite number coprime to n, n+1, n+2, n+3 and n+4.

49, 49, 121, 121, 121, 121, 169, 49, 49, 289, 289, 121, 121, 121, 49, 49, 121, 169, 169, 169, 169, 49, 49, 121, 121, 121, 121, 121, 49, 49, 169, 169, 169, 121, 121, 49, 49, 121, 121, 169, 169, 169, 49, 49, 121, 121, 121, 121, 121, 49, 49, 289, 169, 169, 169, 121, 49

Offset: 1

Author

Labos Elemer, Nov 26 2003

Keywords

• nonn

Crossrefs

Cf. A053669, A053670, A053671, A053672, A053673, A053674.

Cf. A090092, A090093, A090095.

Programs

Mathematica

m=0;Table[fla=1;Do[s=GCD[n, k];s1=GCD[n, k+1]; s2=GCD[n, k+2];s3=GCD[n, k+3];s4=GCD[n, k+4];s5=GCD[n, k+5]; If[Equal[s, 1]&&Equal[s1, 1]&&Equal[s2, 1]&&Equal[s3, 1]&& Equal[s4, 1]&&!PrimeQ[n]&&!Equal[n, 1]&&Equal[fla, 1], m=m+1;Print[n];fla=0], {n, 1, 1000}], {k, 1, 256}]
scn[n_]:=Module[{cn=4},While[!CompositeQ[cn]||!And@@CoprimeQ[ Range[ n,n+4], cn], cn++]; cn]; Array[scn,60] (* Harvey P. Dale, Aug 12 2014 *)

Formula

a(n) = A053673(n)^2.