OFFSET
1,2
COMMENTS
FORMULA
a(n) << n log^2 n, can this be improved? - Charles R Greathouse IV, Jul 25 2024
EXAMPLE
Sequence of integer partitions whose length is equal to their GCD begins: (), (1), (2,2), (4,2), (6,2), (8,2), (10,2), (6,4), (12,2), (3,3,3), (14,2), (16,2), (18,2), (10,4), (20,2), (22,2), (8,6), (24,2), (14,4), (26,2), (28,2), (6,3,3).
MATHEMATICA
Select[Range[200], PrimeOmega[#]==GCD@@Cases[FactorInteger[#], {p_, k_}:>PrimePi[p]]&]
PROG
(PARI) is(n, f=factor(n))=gcd(apply(primepi, f[, 1]))==vecsum(f[, 2]) \\ Charles R Greathouse IV, Jul 25 2024
CROSSREFS
KEYWORD
nonn
AUTHOR
Gus Wiseman, Jul 02 2018
STATUS
approved