A342609 Positive integers that cannot be written in the form k - gpf(k) +- 1 for some integer k, where gpf(k) is the greatest prime factor of k.

17, 49, 161, 197, 199, 209, 251, 391, 419, 449, 649, 685, 769, 799, 883, 967, 1057, 1189, 1249, 1301, 1457, 1481, 1681, 1793, 1937, 1979, 2001, 2029, 2089, 2177, 2209, 2311, 2377, 2379, 2419, 2431, 2449, 2549, 2551, 2575, 2591, 2705, 2729, 2899, 3041, 3073

Offset

1,1

Links

Robert Israel, Table of n, a(n) for n = 1..10000

Maple

f:= proc(n) local g;
  g:= max(numtheory:-factorset(n));
  n-g+1, n-g-1
end proc:
sort(convert({$1..5000} minus map(f, {$1..10001}), list)); # Robert Israel, Apr 12 2021

Crossrefs

Cf. A006530, A076563.

Sequence in context: A146871 A146791 A126371 * A146799 A147201 A146775

Adjacent sequences: A342606 A342607 A342608 * A342610 A342611 A342612

Keyword

nonn

Author

Christian Bagshaw, Mar 16 2021

Status

approved