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A342815
Numbers of the form (2^(2*j + 6*k + 5) - 2^(2*j + 1) - 3)/9, with j,k >= 0.
1
3, 13, 53, 213, 227, 853, 909, 3413, 3637, 13653, 14549, 14563, 54613, 58197, 58253, 218453, 232789, 233013, 873813, 931157, 932053, 932067, 3495253, 3724629, 3728213, 3728269, 13981013, 14898517, 14912853, 14913077, 55924053, 59594069, 59651413, 59652309
OFFSET
1,1
COMMENTS
Sequence is a subsequence of A198584. When any term is iterated using the Collatz function, the last odd integer in the trajectory before 1 is of the form (4^(3*m + 2) - 1)/3.
MATHEMATICA
Take[Sort[Flatten[Table[(2^(2n1+6n2+5) - 2^(2n1+1) - 3)/9, {n1, 0, 20}, {n2, 0, 20}]]], 50]
PROG
(Python)
seq=[]
for n1 in range(20):
for n2 in range(20):
n=(2**(2*n1+6*n2+5) - 2**(2*n1+1) - 3)/9
seq.append(n)
seq.sort()
print(seq[0:50])
CROSSREFS
Union with A342816 gives A198584.
Sequence in context: A065059 A198584 A346382 * A072197 A065838 A052990
KEYWORD
nonn,easy
AUTHOR
Satya Das, Mar 22 2021
STATUS
approved