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Search: id:A101593
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A101593 a(n) = number of m <= 2^n which are in A075190, i.e. such that A056929(m)=0. +0
2
1, 2, 3, 6, 9, 14, 19, 34, 62, 109, 202, 336, 587, 1100, 2003, 3630, 6784, 12607, 23647, 44206, 83510, 157851 (list; graph; listen)
OFFSET

1,2

COMMENT

A056929(m)=0 iff m^2 = (A007491(m)+A053001(m))/2 = average of the next higher and next lower primes.

PROGRAM

(PARI) a(n)=sum(i=2, 2^n, !A056929(i))

(PARI) a(n)=sum(i=2, 2^n, nextprime(i^2)+precprime(i^2)==2*i^2)

(PARI) t=0; vector(15, n, t=sum(i=1/2<<n+1, 1<<n, nextprime(i^2)+precprime(i^2)==2*i^2, t))

(PARI) for(n=16, 30, print1(t=sum(i=2^(n-1)+1, 2^n, nextprime(i^2)+precprime(i^2)==2*i^2, t), ", "))

CROSSREFS

Cf. A056929, A007491, A053001, A075190, A069495.

Sequence in context: A074150 A061925 A073736 this_sequence A084628 A002096 A094055

Adjacent sequences: A101590 A101591 A101592 this_sequence A101594 A101595 A101596

KEYWORD

nonn

AUTHOR

Zak Seidov (zakseidov(AT)yahoo.com) and M. F. Hasler (Maximilian.Hasler(AT)gmail.com), Dec 27 2007

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Last modified November 30 22:12 EST 2008. Contains 150989 sequences.


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