A309454 - OEIS

%I #11 Aug 03 2019 14:19:42

%S 0,6,20,265,1980,11584,11584,246882,1070425,29894430,29894430,

%T 1159795426,9069102398,9069102398,202847123212,2237516341759,

%U 2237516341759,201635099759365,1132157155708193,6017397949439540,17416293134812683,496169890920484689,1613261619087052703

%N The successive approximations up to 7^n for 7-adic integer 6^(1/5).

%F a(0) = 0 and a(1) = 6, a(n) = a(n-1) + 4 * (a(n-1)^5 - 6) mod 7^n for n > 1.

%e a(1) = (   6)_7 = 6,

%e a(2) = (  26)_7 = 20,

%e a(3) = ( 526)_7 = 265,

%e a(4) = (5526)_7 = 1980.

%o (PARI) {a(n) = truncate((6+O(7^n))^(1/5))}

%Y Cf. A309449.

%Y Expansions of p-adic integers:

%Y A290800, A290802 (7-adic, sqrt(-6));

%Y A290806, A290809 (7-adic, sqrt(-5));

%Y A290803, A290804 (7-adic, sqrt(-3));

%Y A210852, A212153 (7-adic, (1+sqrt(-3))/2);

%Y A290557, A290559 (7-adic, sqrt(2));

%Y A309450 (7-adic, 2^(1/5));

%Y A309451 (7-adic, 3^(1/5));

%Y A309452 (7-adic, 4^(1/5));

%Y A309453 (7-adic, 5^(1/5)).

%K nonn

%O 0,2

%A _Seiichi Manyama_, Aug 03 2019