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

Author

Lei Zhou, Oct 07 2011

Keywords

• nonn
• easy

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?

Examples

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

Crossrefs

Cf. A196941, A062241.

Programs

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}]