1,7

Number of twins of prime quadruples with at most n digits. A twin of prime quadruples consists of two prime quadruples with a (minimal) distance of 30.

Table of n, a(n) for n=1..17.

J. Brüggemann, The twins of prime quadruples up to 10^17 [71 MB].

J. Brüggemann, Calculating prime quadruples, its twins, triples and quadruples.

For n=7 the a(7)=4 solutions are: [(1006301, 1006303, 1006307, 1006309), (1006331, 1006333, 1006337, 1006339)], [(2594951, 2594953, 2594957, 2594959), (2594981, 2594983, 2594987, 2594989)], [(3919211, 3919213, 3919217, 3919219), (3919241, 3919243, 3919247, 3919249)], [(9600551, 9600553, 9600557, 9600559), (9600581, 9600583, 9600587, 9600589)].

Cf. A007530, A059925, A338868.

Sequence in context: A026755 A243120 A317378 * A308485 A234143 A217686

Adjacent sequences: A338863 A338864 A338865 * A338867 A338868 A338869

nonn,more

Hans H. Brüggemann, Nov 13 2020

a(17) corrected by Hans H. Brüggemann, Apr 11 2021

approved