641580domain: NAppears in sequencesExpansion of 1/(1-x^3-x^4-x^5-x^6-x^7).at n=43A017820Values of k such that k - 1 and k + 1 are twin primes and 3*k^9 - 1 and 3*k^9 + 1 are also twin primes.at n=11A108134