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A090870 a(n) is the smallest m such that d(m+k-1)=2k for k=1,...,n where d(t)= prime(t+1)-prime(t)(differences of consecutive primes in arithmetic progression). 0
2, 3, 7, 69, 1642, 12073, 12073, 6496152, 118033638, 5575956036 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Is this sequence infinite?

LINKS

Table of n, a(n) for n=1..10.

FORMULA

a(n) = primePi(A016045(n)).

EXAMPLE

a(8)=6496152 because prime(6496152) = 113575727 and 113575727, 113575729, 113575733, 113575739, 113575747, 113575757, 113575769, 113575783, and 113575799 are nine consecutive primes with differences respectively 2, 4, 6, 8, 10, 12, 14, 16.

MATHEMATICA

a[n_] := (For[m=1, !Sum[(d[m+k-1]-2k)^2, {k, n}]==0, m++ ]; m); Do[Print[a[n]], {n, 8}]

CROSSREFS

Cf. A016045, A049232.

Sequence in context: A057736 A181263 A130309 * A088542 A075840 A096225

Adjacent sequences:  A090867 A090868 A090869 * A090871 A090872 A090873

KEYWORD

more,nonn

AUTHOR

Farideh Firoozbakht, Dec 11 2003

EXTENSIONS

Extended and edited by T. D. Noe, May 23 2011

STATUS

approved

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Last modified February 21 02:57 EST 2019. Contains 320364 sequences. (Running on oeis4.)