

A290692


Carmichael numbers of the form p  2 where p is a prime number.


2



561, 2465, 656601, 1909001, 174352641, 230996949, 275283401, 939947009, 1534274841, 3264820001, 5860426881, 6025532241, 25536531021, 36709177121, 53388707681, 54519328481, 56222911361, 101536702401, 105528976961, 180481509681, 196866607601, 239862350001, 329245587161, 347469383801, 347511324161
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OFFSET

1,1


COMMENTS

Rotkiewicz mentioned the first six terms of this sequence at the end of page 59 of his article (Links section). But his list includes 2821 and 46657 (2823 = 3 * 941 and 46659 = 3 * 103 * 151), which should not be there.
Carmichael numbers of the form p + 2 where p is a prime number are 1105, 2821, 6601, 29341, 41041, 52633, ... (see also A272754 for corresponding prime numbers).


LINKS



MAPLE

# Using data file from Richard Pinch
infile:= "carmichael16": Res:= NULL;
do
S:= readline(infile);
if S = 0 then break fi;
L:= sscanf(S, "%d");
if nops(L) <> 1 then break fi;
if isprime(L[1]+2) then Res:= Res, L[1]; fi
od:


MATHEMATICA



PROG

(PARI) isA002997(n) = {my(f); bittest(n, 0) && !for(i=1, #f=factor(n)~, (f[2, i]==1 && n%(f[1, i]1)==1)return) && #f>1}
isok(n) = isprime(n+2) && isA002997(n)


CROSSREFS



KEYWORD

nonn


AUTHOR



EXTENSIONS



STATUS

approved



