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 A136050 Sum of digits of product of twin primes A037074. 2
 6, 8, 8, 8, 26, 17, 26, 17, 8, 17, 17, 26, 26, 26, 17, 26, 35, 35, 26, 26, 8, 35, 26, 17, 26, 35, 44, 26, 17, 35, 35, 35, 35, 26, 35, 26, 17, 26, 26, 26, 17, 35, 26, 35, 26, 35, 26, 17, 26, 17, 35, 35, 26, 26, 35, 35, 26, 35, 26, 35, 26, 26, 26, 35, 26, 44, 35, 26, 26, 35, 44, 35 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Conjecture: except for the initial term, each term is one less than a multiple of 9. - Harvey P. Dale, Dec 02 2016 LINKS Harvey P. Dale, Table of n, a(n) for n = 1..5000 FORMULA a(n) = A007953(A037074(n)). - Michel Marcus, Nov 04 2013 EXAMPLE The product of the first twin primes is 15=3*5, and sum of digits of 15 is 6. MATHEMATICA a = {6}; Do[If[PrimeQ[6n - 1] && PrimeQ[6n + 1], c = IntegerDigits[36n^2 - 1]; b = Total[c]; AppendTo[a, b]], {n, 400}]; a Total[IntegerDigits[Times@@#]]&/@Select[Partition[Prime[Range[500]], 2, 1], #[[2]]- #[[1]]==2&] (* Harvey P. Dale, Dec 02 2016 *) PROG (PARI) lista(nn) = for (x=1, nn, if(prime(x+1)-prime(x)==2, print1(sumdigits(prime(x)*prime(x+1)), ", "))); \\ Michel Marcus, Nov 04 2013 CROSSREFS Cf. A002822, A037074, A007953, A136017. Sequence in context: A157683 A300897 A049110 * A281112 A229020 A113697 Adjacent sequences:  A136047 A136048 A136049 * A136051 A136052 A136053 KEYWORD nonn,base AUTHOR Artur Jasinski, Dec 12 2007 EXTENSIONS First term a(1)=6 inserted by Michel Marcus, Nov 04 2013 STATUS approved

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Last modified September 30 17:12 EDT 2020. Contains 337440 sequences. (Running on oeis4.)