A081653 Greatest common divisor of sums of decimal digits of n and of n-th prime.

1, 1, 1, 1, 1, 2, 1, 2, 1, 1, 2, 1, 1, 1, 1, 1, 2, 1, 1, 2, 1, 4, 1, 1, 1, 2, 1, 2, 1, 1, 2, 5, 1, 1, 2, 1, 1, 1, 2, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 2, 7, 1, 1, 2, 11, 1, 1, 2, 1, 1, 2, 1, 5, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 16, 1, 1, 1, 1, 1, 1, 2, 1, 2, 1, 2, 1, 2, 1, 2, 5, 1

Offset: 1

Author

Reinhard Zumkeller, Mar 25 2003

Keywords

• nonn
• base
• easy

Examples

			a(8) = GCD(A007953(8), A007953(A000040(8))) = GCD(8, A007953(19)) = GCD(8,1+9) = GCD(4*2,5*2) = 2.
		

Crossrefs

Cf. A000040, A007953, A007605, A081652, A066750.

Programs

Mathematica

A081653[n_Integer]:=GCD[Plus@@IntegerDigits[n],Plus@@IntegerDigits[Prime[n]]]; Table[A081653[n],{n,105}] (* Enrique Pérez Herrero, Aug 07 2010 *)

Formula

a(n) = GCD(A007953(n), A007605(n)).