A276591 a(n) is the smallest prime p > a(n-1) such that p - a(n-1) is an (n-1)-almost prime; a(1) = 2.

2, 5, 11, 19, 43, 151, 311, 439, 823, 2551, 6007, 12919, 23159, 35447, 92791, 203383, 535159, 731767, 1124983, 5253751, 6302327, 16919159, 32647799, 103426679, 160049783, 285878903, 386542199, 1066019447, 1468672631, 2676632183, 5092551287, 16366840439, 32472967799

Offset

1,1

Links

Table of n, a(n) for n=1..33.

Example

a(2) - a(1) = 5 - 2 = 3, which is prime (a "1-almost prime");
a(3) - a(2) = 11 - 5 = 6 = 2*3, which is semiprime (2-almost prime).

Crossrefs

Sequence in context: A121606 A166164 A097008 * A051653 A106015 A178316

Adjacent sequences: A276588 A276589 A276590 * A276592 A276593 A276594

Keyword

nonn

Author

Zak Seidov, Nov 16 2016

Extensions

a(32)-a(33) from Jinyuan Wang, Jul 31 2021

Status

approved