A144550 Largest non-twin prime < n-th and (n+1)-th twin primes.

2, 23, 37, 53, 67, 97, 131, 173, 223, 233, 263, 277, 307, 337, 409, 457, 509, 563, 593, 613, 631, 653, 797, 853, 877, 1013, 1039, 1087, 1129, 1223, 1259, 1283, 1297, 1307, 1423, 1447, 1471, 1601, 1613, 1663, 1693, 1709, 1783, 1867, 1913, 1993, 2017, 2069

Offset: 1

Author

Juri-Stepan Gerasimov, Dec 31 2008

Keywords

• nonn

Links

• Harvey P. Dale, Table of n, a(n) for n = 1..1000

Crossrefs

Cf. A077800, A088175.

Programs

Maple

isA077800 := proc(n) isprime(n) and ( isprime(n+2) or isprime(n-2)) ; end proc:
isA007510 := proc(n) isprime(n) and not isA077800(n) ; end proc:
isA144550 := proc(n) isA007510(n) and isA077800( nextprime(n)) ; end proc:
for n from 2 to 2500 do if isA144550(n) then printf("%d,",n) ; end if; end do: # R. J. Mathar, May 01 2010

Mathematica

Module[{nn=400,tps},tps=Union[Flatten[Select[Partition[Prime[Range[nn]],2,1], #[[2]]-#[[1]] == 2&]]];Complement[NextPrime[#,-1]&/@tps,tps]] (* Harvey P. Dale, Jun 23 2022 *)

Formula

{A007510(k): nextprime(A007510(k)) in A077800}. - R. J. Mathar, May 01 2010

Extensions

Corrected (1993 inserted) by R. J. Mathar, May 01 2010