A082669 a(n) = p(n)*(p(n)-1)/2 where p(n) = upper member of n-th pair of twin primes.

10, 21, 78, 171, 465, 903, 1830, 2628, 5253, 5886, 9591, 11325, 16290, 18528, 19701, 26106, 28920, 36585, 39903, 48828, 60726, 88410, 93528, 106953, 136503, 162735, 180300, 191271, 206403, 218130, 328455, 338253, 343206, 368511, 389403

Offset

1,1

Links

Table of n, a(n) for n=1..35.

Formula

a(n) = A006512(n) * (A006512(n) - 1) / 2. - Sean A. Irvine, Dec 18 2025

Maple

ZL:=[]:for p from 1 to 890 do if (isprime(p) and isprime(p+2) ) then ZL:=[op(ZL), (binomial((p+2), p))]; fi; od; print(ZL); # Zerinvary Lajos, Mar 08 2007

Prog

(PARI) tpcomb2(n) = { forprime(x=3, n, if(isprime(x-2), print1((x)*(x-1)/2" ") ) ) }

Crossrefs

Cf. A006512.

Sequence in context: A356761 A096564 A041196 * A215574 A146083 A321722

Adjacent sequences: A082666 A082667 A082668 * A082670 A082671 A082672

Keyword

easy,nonn

Author

Cino Hilliard, May 18 2003

Extensions

Revised by Sean A. Irvine, Dec 18 2025

Status

approved