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 A240924 Digital root of squares of numbers not divisible by 2, 3 or 5. 2

%I

%S 1,4,4,7,1,1,7,4,7,1,7,4,4,7,1,7,4,7,1,1,7,4,4,1,1,4,4,7,1,1,7,4,7,1,

%T 7,4,4,7,1,7,4,7,1,1,7,4,4,1,1,4,4,7,1,1,7,4,7,1,7,4,4,7,1,7,4,7,1,1,

%U 7,4,4,1

%N Digital root of squares of numbers not divisible by 2, 3 or 5.

%C This period 24 repeating sequence is palindromic.

%e The first 8 numbers not divisible by 2, 3 or 5 are 1,7,11,13,17,19,23,29; with squares 1,49,121,169,289,361,529,841 and digital root sequence of 1,4,4,7,1,1,7,4.

%o (Python)

%o A240924 = [1 + (n*n-1) % 9 for n in range(1,10**3,2) if n % 3 and n % 5 ]

%o # _Chai Wah Wu_, Sep 03 2014

%Y Cf. A007775, A166923.

%K nonn,base,easy

%O 1,2

%A _Gary Croft_, Aug 15 2014

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Last modified January 22 13:50 EST 2019. Contains 319364 sequences. (Running on oeis4.)