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

1,3

Comments

If necessary the result is rounded to the nearest integer.

Links

Table of n, a(n) for n=1..67.

Eric Weisstein's World of Mathematics, Twin Primes

Example

(59 + 61) / (5+9+6+1) = 120/21 = 5.7 = 6 (rounded to the nearest integer)
107 and 109 are twin primes.
Hence (107 + 109) / (1+0+7+1+0+9) = 216/18 = 12

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_] := Round[2 (n + 1)/(Plus @@ IntegerDigits[n] + Plus @@ IntegerDigits[n + 2])]; f@# & /@ Select[ Prime@ Range@ 1000, PrimeQ[# + 2] &] (* Robert G. Wilson v, Aug 16 2011 *)

Crossrefs

Cf. A001359.

Sequence in context: A013679 A096428 A091007 * A110638 A154995 A154973

Adjacent sequences: A180153 A180154 A180155 * A180157 A180158 A180159

Keyword

base,nonn,less

Author

Parthasarathy Nambi, Aug 14 2010

Extensions

More terms from Harvey P. Dale, Mar 23 2011.

Status

approved