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A331596 Number of distinct prime factors of gcd(A122111(n), A241909(n)). 4
0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 2, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 2, 1, 2, 1, 1, 1, 2, 1, 1, 2, 1, 1, 2, 1, 1, 1, 1, 2, 2, 1, 1, 1, 2, 1, 2, 1, 1, 1, 1, 1, 2, 1, 2, 2, 1, 1, 2, 2, 1, 1, 1, 1, 2, 1, 2, 2, 1, 1, 1, 1, 1, 1, 2, 1, 2, 1, 1, 1, 2, 1, 2, 1, 2, 1, 1, 2, 2, 1, 1, 2, 1, 1, 3 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,15

LINKS

Antti Karttunen, Table of n, a(n) for n = 1..65537

Index entries for sequences computed from indices in prime factorization

FORMULA

a(n) = A001221(A331596(n)) = A001221(gcd(A122111(n), A241909(n))).

a(n) = A001222(A331597(n)).

MATHEMATICA

Array[PrimeNu@ If[# == 1, 1, GCD @@ {Block[{k = #, m = 0}, Times @@ Power @@@ Table[k -= m; k = DeleteCases[k, 0]; {Prime@ Length@ k, m = Min@ k}, Length@ Union@ k]] &@ Catenate[ConstantArray[PrimePi[#1], #2] & @@@ #], Function[t, Times @@ Prime@ Accumulate[If[Length@ t < 2, {0}, Join[{1}, ConstantArray[0, Length@ t - 2], {-1}]] + ReplacePart[t, Map[#1 -> #2 & @@ # &, #]]]]@ ConstantArray[0, Transpose[#][[1, -1]]] &[# /. {p_, e_} /; p > 0 :> {PrimePi@ p, e}]} &@ FactorInteger[#]] &, 105] (* Michael De Vlieger, Jan 24 2020, after JungHwan Min at A122111. *)

PROG

(PARI) A331596(n) = omega(gcd(A122111(n), A241909(n)));

CROSSREFS

Cf. A001221, A331596, A335197.

Sequence in context: A101428 A307223 A321787 * A023586 A023584 A015182

Adjacent sequences:  A331593 A331594 A331595 * A331597 A331598 A331599

KEYWORD

nonn

AUTHOR

Antti Karttunen, Jan 22 2020

STATUS

approved

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Last modified April 21 13:23 EDT 2021. Contains 343153 sequences. (Running on oeis4.)