A309067 Index of A053319(n) in A014574; -1 if it doesn't exist.

-1, 2, 2, 3, 3, 4, 3, 5, 2, 5, 3, 5, 3, 2, 5, 3, 5, 3, 5, -1, 8, 3, 5, 7, -1, 5, 4, -1, 4, 12, 3, 2, 5, -1, 11, 3, 4, 3, 5, 7, -1, -1, 3, 3, 4, 10, -1, 5, 2, -1, 3, -1, 5, -1, -1, -1, 2, -1, 4, -1, 5, -1, 2, -1, 4, 3, -1, 5, 6, 5, 6, -1, 6, -1, 5, -1, 4, 7, 3, -1, 5, -1, -1, -1, 2, 6, 5, 5, 3, 4

Offset

1,2

Links

Table of n, a(n) for n=1..90.

Mathematica

ind[v_, e_] := If[Length[(p = Position[v, _?(# == e &)])] == 0, -1, p[[1]]]; tpmidQ[n_] := And @@ PrimeQ[n + {-1, 1}]; tp = Select[Range[10^4], tpmidQ]; d = Differences[tp]; ind[tp, #] & /@ d // Flatten (* Amiram Eldar, Jul 12 2019 *)

Crossrefs

Cf. A014574, A053319, A309066.

Sequence in context: A110266 A377107 A349138 * A205561 A323636 A375115

Adjacent sequences: A309064 A309065 A309066 * A309068 A309069 A309070

Keyword

sign

Author

Dmitry Kamenetsky, Jul 10 2019

Status

approved