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%I #17 May 10 2024 11:16:33
%S 27,165,8021,12408149,19607957362005,32439509492992549521282389,
%T 58947232705679751034215288252890081792789279233365,
%U 259166427025070423330595967015238989905128148712607202753574381749095993394717720069452733214971221
%N The n-th iterate of 27 with A371094.
%H Antti Karttunen, <a href="/A372444/b372444.txt">Table of n, a(n) for n = 0..10</a>
%F a(0) = 27; for n > 0, a(n) = A371094(a(n-1)).
%o (PARI)
%o A371094(n) = { my(m=1+3*n, e=valuation(m,2)); ((m*(2^e)) + (((4^e)-1)/3)); };
%o A372444(n) = { my(x=27); while(n, x=A371094(x); n--); (x); };
%Y Cf. A371094.
%Y Column 7 of A371102, column 14 of A372282.
%Y Column 1 of A372560.
%Y Sequences derived from this one:
%Y A372443 obtained when Reduced Collatz-function R is applied to a(n-1), for n > 0,
%Y A372445 column index of a(n) in array A257852,
%Y A372448 the 2-adic valuation of 1 + 3*a(n), equal to row index of a(n) in array A257852,
%Y A372449 binary lengths minus 1; their first differences: A372451,
%Y A372452 number of terms of A086893 in the interval [a(n), a(1+n)],
%Y A372454 the difference between a(n) and the term of A086893 with the same binary length.
%K nonn
%O 0,1
%A _Antti Karttunen_, May 01 2024
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