A276641 Number of digits in 2^A000668(n)-1.
1, 3, 10, 39, 2466, 39457, 157827, 646456993, 694127911065419642, 186328542329173367306815834, 48844909400338823199277929902126, 51217599719369681875006054625051616350
Offset: 1
Links
- Ivan Panchenko, Table of n, a(n) for n = 1..18
- MathWorld, Double Mersenne Number.
- Wikipedia, Double Mersenne number.
Programs
-
PARI
next_a000668(n) = my(expo=nextprime(ceil(log(n+1)/log(2)))); while(!ispseudoprime(2^expo-1), expo=nextprime(expo+1)); 2^expo-1 terms(n) = my(p=3, i=0); while(i < n, print1(#Str(2^p-1), ", "); i++; p=next_a000668(p+1)) terms(7) \\ print initial seven terms
Extensions
a(8)-a(12) from Ivan Panchenko, Apr 11 2018
Comments