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Numbers which converge to 7 under repeated application of the powertrain map of A133500.
10

%I #6 Jul 27 2019 10:08:08

%S 7,71,75,107,117,127,137,147,157,167,177,187,197,207,307,407,507,523,

%T 543,607,707,711,723,747,751,807,907,1071,1075,1171,1175,1271,1275,

%U 1371,1375,1471,1475,1571,1575,1671,1675,1771,1775,1871,1875,1971,1975,2071

%N Numbers which converge to 7 under repeated application of the powertrain map of A133500.

%e 75 -> 7^5 = 16807 -> 1^6*8^0*7 = 7.

%Y Cf. A133500, A133501, A135384, A135385, A309385, A326733, A326734, A326735, A326736, A326737, A326738, A326739, A326741, A326742.

%K nonn,base,easy

%O 1,1

%A _Martin Renner_, Jul 22 2019