A372444 The n-th iterate of 27 with A371094.

27, 165, 8021, 12408149, 19607957362005, 32439509492992549521282389, 58947232705679751034215288252890081792789279233365, 259166427025070423330595967015238989905128148712607202753574381749095993394717720069452733214971221

Offset: 0

Author

Antti Karttunen, May 01 2024

Keywords

• nonn

Links

• Antti Karttunen, Table of n, a(n) for n = 0..10

Crossrefs

Cf. A371094.

Column 7 of A371102, column 14 of A372282.

Column 1 of A372560.

Sequences derived from this one:

A372443 obtained when Reduced Collatz-function R is applied to a(n-1), for n > 0,

A372445 column index of a(n) in array A257852,

A372448 the 2-adic valuation of 1 + 3*a(n), equal to row index of a(n) in array A257852,

A372449 binary lengths minus 1; their first differences: A372451,

A372452 number of terms of A086893 in the interval [a(n), a(1+n)],

A372454 the difference between a(n) and the term of A086893 with the same binary length.

Programs

PARI

A371094(n) = { my(m=1+3*n, e=valuation(m,2)); ((m*(2^e)) + (((4^e)-1)/3)); };
A372444(n) = { my(x=27); while(n, x=A371094(x); n--); (x); };

Formula

a(0) = 27; for n > 0, a(n) = A371094(a(n-1)).