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A064015 Numbers k such that sopf(k)*nud(k) = pi(k), where sopf(k)=A008472, nud(k)=A034444 and pi(k)=A000720. 0
1, 8, 72, 135, 504, 726, 3431, 5313, 8614, 10249, 28721, 45705, 83832, 115111, 116057, 235781, 262844, 349351, 396815, 530205, 680229, 2140452, 3514448, 5092315, 5093695, 9520080, 12154006, 12207991, 12213847, 13802199, 13806381, 13807119, 29213727, 115315480 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..34.

MATHEMATICA

aQ[n_] := Plus @@ (p = FactorInteger[n][[;; , 1]]) * 2^Length[p] == PrimePi[n]; Join[{1}, Select[Range[2, 10^4], aQ]] (* Amiram Eldar, Nov 14 2019 *)

PROG

(PARI) nud(n) = 2^omega(n);

sopf(n)=fac=factor(n); s=0; for(i=1, matsize(fac)[1], s=s+fac[i, 1]); return(s);

for(n=1, 10^6, if(sopf(n)*nud(n)==primepi(n), print1(n, ", "))) \\ edited by Michel Marcus, Nov 14 2019

CROSSREFS

Cf. A008472, A034444, A000720.

Sequence in context: A115693 A112403 A043932 * A044576 A104453 A254371

Adjacent sequences: A064012 A064013 A064014 * A064016 A064017 A064018

KEYWORD

nonn

AUTHOR

Jason Earls, Sep 06 2001

EXTENSIONS

a(11)-a(34) from Amiram Eldar, Nov 14 2019

STATUS

approved

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Last modified February 7 02:40 EST 2023. Contains 360111 sequences. (Running on oeis4.)