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A105323 Numbers of the form 41*(2*10^n+1) where (2*10^n+1)/3 is prime (n is in the sequence A096507). 3
861, 8241, 82000041, 8200000041, 82000000041, 8200000000041, 8200000000000000000041, 8200000000000000000000041, 8200000000000000000000000000000000000000041 (list; graph; refs; listen; history; internal format)
OFFSET

1,1

COMMENTS

A105323=41*A093170=41*(2*10^A096507+1)=41*(2*10^(A056657+1)+1). If m is in the sequence then d(m)*reversal(m)=sigma(m) (see A104907). So this sequence is a subsequence of A104907.

EXAMPLE

861 is in the sequence because 861=41*(2*10^1+1); (2*10^1+1)/3=7 and 7 is prime.

MATHEMATICA

Do[If[PrimeQ[(2*10^n + 1)/3], Print[41*(2*10^n + 1)]], {n, 63}]

CROSSREFS

Cf. A104907, A056657, A096507, A093170.

Sequence in context: A187281 A108822 A115749 * A206756 A203272 A184451

Adjacent sequences:  A105320 A105321 A105322 * A105324 A105325 A105326

KEYWORD

nonn

AUTHOR

Farideh Firoozbakht (mymontain(AT)yahoo.com), Apr 16 2005

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Last modified February 14 20:38 EST 2012. Contains 205663 sequences.