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Search: id:A137443
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| A137443 |
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First n-digit prime in consecutive digits of e. |
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+0
1
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| 7, 71, 281, 4523, 74713, 904523, 6028747, 72407663, 360287471, 7427466391, 75724709369, 749669676277, 8284590452353, 99959574966967, 724709369995957, 2470936999595749, 28459045235360287, 571382178525166427
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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If the "2" at the beginning of e is included, the only values for n <= 1000 that change are a(1) = 2, a(3) = 271, and a(85) = 2718281828459045235360287471352662497757247093699959574966967627724076630353547594571.
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LINKS
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Dan Drake, Table of n, a(n) for n = 1..1000
Pegg, E. Jr. and Weisstein, E. W. Mathematica's Google Aptitude. MathWorld Headline news, Oct 13, 2004.
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EXAMPLE
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7427466391 is the first 10-digit prime found in consecutive digits of e, so a(10) = 7427466391.
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PROGRAM
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Sage (http://sagemath.org, replace leading dots by spaces):
def a(digits):
..bits = 0
..pos = 0
..while True:
....bits += (digits * 4) + 50
....decimals = RealField(bits, rnd='RNDZ')(exp(1)).frac().str()[2:]
....for s in range(pos, len(decimals) - digits + 1):
......if decimals[s] != '0':
........i = Integer(decimals[s:s+digits])
........if i.is_prime():
..........return i
....pos = len(decimals) - digits + 1
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CROSSREFS
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Cf. A095926.
Sequence in context: A142928 A069634 A069619 this_sequence A100465 A107601 A069591
Adjacent sequences: A137440 A137441 A137442 this_sequence A137444 A137445 A137446
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KEYWORD
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base,nonn
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AUTHOR
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Dan Drake (ddrake(AT)member.ams.org), Apr 18 2008
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