A101416 Nearest k to j such that k*(2^j-1)-1 is prime where j=A000043(n) and 2^j-1 = Mersenne-prime(n) = A000668(n). If there are two k values equidistant from j, each of which produces a prime, the larger of the two gets added to the sequence.
2, 2, 2, 6, 20, 14, 32, 90, 72, 80, 230, 80, 560, 740, 1542, 1782, 450, 828, 2562, 3936, 12474, 9288, 10224, 16022, 11088, 31034, 53972, 92372
Offset: 1
Examples
n=7, j=A000043(7)=19, A000668(7)=524287, then k=6 or k=32 are the nearest values to j which produce primes so we take the larger of the two k values for a(7)=32.
Extensions
a(5)=20, a(20)=3936 corrected, other terms verified, a(27)-a(28) extended by Ray Chandler, Apr 16 2009