login

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).

A089180
a(n) is the smallest number m such that d(m) = d(m+1) = ... = d(m+n), where d(k) = prime(k+1) - prime(k) (A001223).
12
2, 54, 654926, 6904737
OFFSET
1,1
COMMENTS
a(5) is greater than 105000000.
The a(n)-th prime is the smallest start of n+2 consecutive primes in arithmetic progression. - Jens Kruse Andersen, Jun 14 2014
LINKS
J. K. Andersen, The minimal CPAP-k.
L. J. Lander and T. R. Parkin, Consecutive primes in arithmetic progression, Math. Comp. vol. 21 no. 99 (1967) p. 489.
G. W. Polites, Prime Desert n-Tuplets, Amer. Math. Monthly vol. 95 no. 2 (1988) pp. 98-104.
FORMULA
A000040[a(n)]=A006560(n+2). - R. J. Mathar, Aug 10 2007
a(n) = A000720(A006560(n+2)). - Jens Kruse Andersen, Jun 14 2014
EXAMPLE
a(3) = 659426 because d(659426) = d(659426+1) = d(659426+2) = d(6594286+3) or 9843019, 9843049, 9843079, 9843109, 9843139 are five consecutive primes with same difference and prime(659426) = 9843019 is the smallest prime number with this property.
Also a(4) = 6904737 because d(6904737) = d(6904737+1) = ... = d(6904737+4) or 121174811, 121174841, 121174871, 121174901, 121174931, 121174961 are six consecutive primes with same difference and prime(6904737) = 121174811 is the smallest prime number with this property.
CROSSREFS
Sequence in context: A117681 A221603 A359183 * A034013 A340211 A356985
KEYWORD
more,nonn
AUTHOR
Farideh Firoozbakht, Dec 07 2003
STATUS
approved