A180156 Sequence from adding the twin primes and dividing by the digit sum of twin primes.

1, 1, 4, 2, 4, 7, 6, 8, 34, 12, 12, 14, 13, 16, 11, 19, 23, 20, 24, 52, 23, 40, 48, 39, 58, 35, 40, 41, 54, 40, 60, 69, 46, 41, 49, 136, 172, 100, 118, 91, 128, 117, 71, 78, 217, 126, 95, 121, 99, 71, 107, 120, 79, 71, 144, 75, 104, 78, 129, 100, 74, 169, 174, 116, 352, 203, 238

Offset: 1

Author

Parthasarathy Nambi, Aug 14 2010

Keywords

• base
• nonn
• less
• changed

Comments

If necessary the result is rounded to the nearest integer.

This sequence uses round(x) = floor(1/2 + x). - Jason Yuen, Sep 01 2025

Examples

			a(7) = round((59 + 61) / (5+9+6+1)) = round(120/21) = round(5.714...) = 6.
a(10) = round((107 + 109) / (1+0+7+1+0+9)) = round(216/18) = 12.
		

Links

• Eric Weisstein's World of Mathematics, Twin Primes

Crossrefs

Cf. A001359.

Programs

Mathematica

Floor[1/2+Total[#]/Total[Flatten[IntegerDigits/@#]]]&/@ Select[Partition[Prime[Range[500]],2,1], Last[#]-First[#]==2&]  (* Harvey P. Dale, Mar 23 2011 *)
f[n_] := Floor[1/2 + 2 (n + 1)/(Plus @@ IntegerDigits[n] + Plus @@ IntegerDigits[n + 2])]; f@# & /@ Select[ Prime@ Range@ 1000, PrimeQ[# + 2] &] (* Robert G. Wilson v, Aug 16 2011 *)

Extensions

More terms from Harvey P. Dale, Mar 23 2011