A196942 a(n) is the prime order of sequence A196941.

0, 1, 1, 1, 1, 2, 1, 1, 1, 2, 1, 2, 2, 2, 1, 1, 1, 2, 1, 2, 2, 3, 1, 2, 2, 2, 2, 2, 2, 2, 1, 1, 1, 2, 1, 2, 2, 2, 1, 2, 2, 2, 2, 2, 3, 3, 1, 2, 2, 2, 2, 3, 2, 2, 2, 2, 2, 2, 2, 3, 2, 2, 1, 1, 1, 2, 1, 3, 2, 4, 1, 2, 2, 2, 2, 3, 2, 3, 1, 2, 2, 2, 2, 2, 2, 2, 2

Offset

2,6

Comments

Assuming 1 is the 0th prime, as what in Mathematica: PrimePi[1] = 0.

So far the first occurrence of this sequence agree with A062241 and A045535. Is this a coincidence or a theorem?

Links

Table of n, a(n) for n=2..88.

Example

A196941(3) = 2, which is the first prime number, so a(3) = 1;

Mathematica

FactorSet[seed_] := Module[{fset2, a, l, i}, a = FactorInteger[seed]; l = Length[a]; fset2 = {}; Do[fset2 = Union[fset2, {a[[i]][[1]]}], {i, 1, l}]; fset2]; Table[min = n; Do[r = n - k; s = Union[FactorSet[k], FactorSet[r]]; If[a = s[[Length[s]]]; a < min, min = a], {k, 1, IntegerPart[n/2]}]; PrimePi[min], {n, 2, 88}]

Crossrefs

Cf. A196941, A062241.

Sequence in context: A212185 A270928 A290257 * A184304 A363298 A025909

Adjacent sequences: A196939 A196940 A196941 * A196943 A196944 A196945

Keyword

nonn,easy

Author

Lei Zhou, Oct 07 2011

Status

approved