OFFSET
0,3
COMMENTS
In p-adic field, the exponential function exp(x) is defined as Sum_{k>=0} x^k/k!. When extended to a function over the metric completion of the p-adic field, exp(x) has radius of convergence p^(-1/(p-1)) (i.e., exp(x) converges for x such that |x|_p < p^(-1/(p-1)), where |x|_p is the p-adic metric). As a result, for odd primes p, exp(p) is well-defined in p-adic field, and exp(4) is well defined in 2-adic field.
a(n) is the multiplicative inverse of A309904(n) modulo 7^n.
LINKS
Wikipedia, p-adic number
PROG
(PARI) a(n) = lift(exp(-7 + O(7^n)))
KEYWORD
nonn
AUTHOR
Jianing Song, Aug 21 2019
STATUS
approved