A096711 Number of balanced primes (A090403) less than 10^n.

1, 8, 57, 308, 1989, 13161, 94939

Offset

1,2

Comments

The average number of balanced primes, p_n, seems to reach a maximum at the 85th prime, 439, of 32 balanced primes.

A096711(n)/A006880(n) begins 25%, 32%, 33.93%, 25.06%, 20.74%

Links

Table of n, a(n) for n=1..7.

Mathematica

f[n_] := f[n] = Block[{c = 0, k = 1, p = Prime[n], s = Plus @@ Table[Prime[i], {i, n - 1, n + 1}]}, While[k != n - 1, If[s == (2k + 1)p, Return[1]]; k++; s = s + Prime[n - k] + Prime[n + k]]; 0]; f[1] = 0; Do[ f[n], {n, 10000}]; s = Prime[ Select[ Range[ 10000], f[ # ] == 1 &]]; Table[ Length[ Select[s, # < 10^n &]], {n, 5}]

Crossrefs

Cf. A090403.

Sequence in context: A296721 A283693 A297453 * A282394 A244201 A079926

Adjacent sequences: A096708 A096709 A096710 * A096712 A096713 A096714

Keyword

nonn

Author

Robert G. Wilson v, Jul 03 2004

Extensions

a(6)-a(7) from Donovan Johnson, Apr 09 2010

Status

approved