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A343197
Numbers k such that A025281(k) is prime.
2
2, 3, 6, 16, 29, 30, 34, 35, 36, 39, 57, 59, 76, 77, 88, 94, 101, 112, 126, 166, 177, 192, 206, 228, 238, 248, 251, 258, 259, 260, 271, 275, 276, 282, 299, 317, 318, 333, 345, 347, 353, 354, 370, 378, 386, 391, 402, 407, 417, 437, 445, 452, 455, 466, 470, 475, 478, 489, 494, 499, 508, 521, 530
OFFSET
1,1
COMMENTS
Numbers k such that A343196(k) = 1.
LINKS
EXAMPLE
a(4) = 16 is a term because A025281(16) = A001414(16!) = 101.
MAPLE
sopf:= proc(n) local t; add(t[1]*t[2], t=ifactors(n)[2]) end proc:
R:= NULL: count:= 0: T:= 0:
for n from 2 while count < 100 do
T:= T + sopf(n);
if isprime(T) then R:= R, n; count:= count+1 fi;
od:
R;
MATHEMATICA
Select[Range[2, 530], PrimeQ@ Total@ Flatten[ConstantArray[#1, #2] & @@@ FactorInteger[#]] &[#!] &] (* Michael De Vlieger, Apr 07 2021 *)
PROG
(Python)
from sympy import isprime, factorint
A343197_list = [n for n in range(2, 10**6) if isprime(sum(sum(p*e for p, e in factorint(i).items()) for i in range(2, n+1)))] # Chai Wah Wu, Apr 09 2021
CROSSREFS
KEYWORD
nonn
AUTHOR
J. M. Bergot and Robert Israel, Apr 07 2021
STATUS
approved