A095958 - OEIS

A095958

Twin prime pairs concatenated in decimal representation.

35, 57, 1113, 1719, 2931, 4143, 5961, 7173, 101103, 107109, 137139, 149151, 179181, 191193, 197199, 227229, 239241, 269271, 281283, 311313, 347349, 419421, 431433, 461463, 521523, 569571, 599601, 617619, 641643, 659661

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OFFSET

1,1

COMMENTS

a(n) mod 3 = 0 for n>1, proof: A007953(a(n)) = 2*A007953(A001359(n)+1) and A007953(A001359(n)) mod 3 = 2 for n>1, therefore A007953(a(n)) mod 3 = 0.

LINKS

Reinhard Zumkeller, Table of n, a(n) for n = 1..10000

EXAMPLE

29 = A001359(5), 29 + 2 = 31 = A006512(5): a(5) = 2931.

MATHEMATICA

concat[{a_, b_}]:=FromDigits[Flatten[IntegerDigits/@{a, b}]]; concat/@ Select[Partition[ Prime[ Range[150]], 2, 1], #[[2]]-#[[1]]==2&] (* Harvey P. Dale, Apr 20 2012 *)

PROG

(Haskell)

a095958 n = a095958_list !! (n-1)

a095958_list = f $ map show a077800_list :: [Integer] where

f (t:t':ts) = read (t ++ t') : f ts

-- Reinhard Zumkeller, Apr 20 2012

(Magma) [Seqint( Intseq(NthPrime(n+1)) cat Intseq(NthPrime(n)) ): n in [1..150 ]| NthPrime(n+1)-NthPrime(n) eq 2 ]; // Marius A. Burtea, Mar 21 2019

CROSSREFS

Cf. A045533, A001359, A006512.

Cf. A077800, subsequence of A045533.

Sequence in context: A351095 A267738 A219806 * A244057 A219457 A343099

Adjacent sequences: A095955 A095956 A095957 * A095959 A095960 A095961

KEYWORD

nonn,base

AUTHOR

Reinhard Zumkeller, Jul 14 2004

STATUS

approved