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A270267 Carmichael numbers (A002997) that are the sum of three consecutive primes. 2
252601, 410041, 1615681, 2113921, 10606681, 10877581, 11921001, 26932081, 44238481, 54767881, 82929001, 120981601, 128697361, 208969201, 246446929, 255160621, 278152381, 280067761, 311388337, 325546585, 334783585, 416964241, 533860309, 593234929, 672389641 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

In other words, Carmichael numbers of the form p + q + r where p, q and r are consecutive primes.

If a Carmichael number is the sum of n consecutive primes, it is so obvious that the minimum value of n is 3.

Intersection of A002997 and A034961.

LINKS

Amiram Eldar, Table of n, a(n) for n = 1..10000

EXAMPLE

84191, 84199 and 84211 are consecutive primes and sum of them is 252601 that is a Carmichael number.

136657, 136691 and 136693 are consecutive primes and sum of them is 410041 that is a Carmichael number.

538553, 538561 and 538567 are consecutive primes and sum of them is 1615681 that is a Carmichael number.

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}

a034961(n) = my(p=prime(n), q=nextprime(p+1)); p+q+nextprime(q+1);

for(n=1, 1e6, if(isA002997(a034961(n)), print1(a034961(n), ", ")));

CROSSREFS

Cf. A002997, A034961.

Sequence in context: A113567 A083628 A212843 * A255441 A210074 A230484

Adjacent sequences:  A270264 A270265 A270266 * A270268 A270269 A270270

KEYWORD

nonn

AUTHOR

Altug Alkan, Mar 14 2016

EXTENSIONS

More terms from Amiram Eldar, Jun 25 2019

STATUS

approved

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Last modified September 17 04:49 EDT 2019. Contains 327119 sequences. (Running on oeis4.)