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A120120 Number of n-digit prime quadruplets. 4
1, 3, 7, 26, 128, 733, 3869, 23620, 152141, 1028789, 7188960, 51672312, 381226246, 2873279651 (list; graph; refs; listen; history; text; internal format)
OFFSET

2,2

REFERENCES

J.-L. Baril, Classical sequences revisited with permutations avoiding dotted pattern, Electronic Journal of Combinatorics, 18 (2011), #P178; http://www.combinatorics.org/Volume_18/PDF/v18i1p178.pdf.

LINKS

Table of n, a(n) for n=2..15.

T. R. Nicely, Enumeration to 1.6*10^15 of the prime quadruplets.

EXAMPLE

a(3) = 3 because there are three three-digit prime quadruples: {101, 103, 107, 109}, {191, 193, 197, 199} and {821, 823, 827, 829}.

CROSSREFS

Cf. A006879, A070076, A038801.

Sequence in context: A158561 A252786 A108217 * A126472 A019059 A175198

Adjacent sequences:  A120117 A120118 A120119 * A120121 A120122 A120123

KEYWORD

nonn,base

AUTHOR

Julien Peter Benney (jpbenney(AT)ftml.net), Aug 15 2006, Aug 19 2006

EXTENSIONS

a(6) corrected and a(15) supplied by Jon E. Schoenfield, Aug 27 2006

STATUS

approved

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Last modified May 22 16:38 EDT 2015. Contains 257745 sequences.