A081652 Greatest common divisor of n and sum of decimal digits of n-th prime.
1, 1, 1, 1, 1, 2, 1, 2, 1, 1, 1, 2, 1, 7, 1, 8, 1, 1, 1, 4, 1, 2, 1, 1, 1, 2, 1, 4, 1, 5, 1, 1, 11, 1, 7, 1, 1, 2, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 2, 1, 1, 1, 2, 1, 1, 1, 2, 1, 1, 1, 11, 1, 1, 1, 2, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 8, 1, 1, 1, 4, 1, 2, 1, 8, 1, 2, 1, 10, 1, 17, 1, 4
Offset: 1
Examples
a(16) = GCD(16, A007953(A000040(16))) = GCD(16, A007953(53)) = GCD(16,5+3) = GCD(8*2,8) = 8.
Programs
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Mathematica
Table[GCD[n,Total[IntegerDigits[Prime[n]]]],{n,110}] (* Harvey P. Dale, Jul 12 2012 *)
Formula
a(n) = GCD(n, A007605(n)).