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A080700
Product of upper bound twin-prime-indexed primes and their lower bound twin prime.
0
33, 85, 451, 1139, 3683, 7831, 16697, 26057, 56863, 64093, 109189, 130673, 194573, 223661, 239749, 328469, 363997, 468329, 519007, 647191, 815797, 1218871, 1301189, 1520839, 1959481, 2363057, 2648179, 2817839, 3068467, 3257437
OFFSET
1,1
FORMULA
Let prime(i) = i-th prime, let twin(n) = (P, Q) be n-th pair of twin primes; sequence gives prime(Q)*P.
EXAMPLE
The 3rd pair of twin primes is twin(3) = (11,13), prime(13) = 41, a(3) = 41*11 = 451.
MATHEMATICA
Prime[Last[#]]First[#]&/@Select[Partition[Prime[Range[200]], 2, 1], Last[#]- First[#] ==2&] (* Harvey P. Dale, Apr 23 2011 *)
PROG
(PARI) twipxpindex3(n) = {sr=0; pr=1; for(x=1, n, p1=prime(x); p2=prime(x+1); if((p2-p1)==2, pr=p1*prime(prime(x+1)); sr+=1.0/pr; print1(pr" ")); ); print(); print(sr) }
CROSSREFS
Sequence in context: A039833 A355711 A250732 * A292366 A080200 A067705
KEYWORD
easy,nonn
AUTHOR
Cino Hilliard, Mar 04 2003
STATUS
approved