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A232460
a(n) = 2^(2^n) - 5.
3
-3, -1, 11, 251, 65531, 4294967291, 18446744073709551611, 340282366920938463463374607431768211451, 115792089237316195423570985008687907853269984665640564039457584007913129639931
OFFSET
0,1
COMMENTS
For n >= 3, a(n) is not of the form 2^k + p, where p is a prime. Therefore every term greater than 11 is in A006285 (de Polignac numbers).
LINKS
Wacław Sierpiński, Elementary Theory of Numbers, Monografie Matematyczne 42 (1964), p. 415.
FORMULA
a(n) = A000215(n) - 6.
a(0) = - 3; a(n) = (a(n-1) + 5)^2 - 5, n >= 1.
MATHEMATICA
Table[2^(2^n) - 5, {n, 0, 8}]
PROG
(Magma) [2^(2^n)-5 : n in [0..8]]
(PARI) for(n=0, 8, print1(2^(2^n)-5, ", "));
(Python)
def A232460(n): return (1<<(1<<n))-5 # Chai Wah Wu, Jul 19 2022
CROSSREFS
Cf. A006285.
Sequence in context: A002589 A048522 A365035 * A337205 A287197 A118020
KEYWORD
sign,easy
AUTHOR
STATUS
approved