A021005 Let q_k=p(p+2) be product of k-th pair of twin primes; sequence gives values of p such that (q_k)^2 > q_{k-i}q_{k+i} for all 1 <= i <= k-1.

3, 11, 29, 59, 101, 137, 179, 191, 227, 419, 521, 569, 599, 809, 821, 1019, 1229, 1277, 1289, 1607, 1667, 1871, 2081

Offset

1,1

Links

Charles R Greathouse IV, Table of n, a(n) for n = 1..10000

Example

E.g. (11*13)^2 > (5*7)*(17*19): (11*13)^2 > (3*5)*(29*31).

Prog

(PARI) twins=List(); p=3; forprime(q=5, 1e5, if(q-p==2, listput(twins, q)); p=q); for(k=1, (#twins+1)\2, for(i=1, k-1, if(twins[k]^2 < twins[k-i]*twins[k+i], next(2))); print1(twins[k]-2", ")) \\ Charles R Greathouse IV, Apr 02 2014

Crossrefs

Cf. A028388, A021007.

Sequence in context: A111693 A100032 A069350 * A053845 A172102 A242807

Adjacent sequences: A021002 A021003 A021004 * A021006 A021007 A021008

Keyword

nonn

Author

Naohiro Nomoto

Extensions

a(1) inserted by Charles R Greathouse IV, Apr 02 2014

Status

approved