Consecutive primes with ascending or descending differences: Difference between revisions
Consecutive primes with ascending or descending differences (view source)
Revision as of 15:52, 4 April 2021
, 3 years agoAdded Wren
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Longest run(s) of descending prime gaps up to 1000000:
322171 (22) 322193 (20) 322213 (16) 322229 (8) 322237 (6) 322243 (4) 322247 (2) 322249
752207 (44) 752251 (12) 752263 (10) 752273 (8) 752281 (6) 752287 (4) 752291 (2) 752293
</pre>
=={{header|Wren}}==
{{libheader|Wren-math}}
<lang ecmascript>import "/math" for Int
var LIMIT = 999999
var primes = Int.primeSieve(LIMIT)
var longestSeq = Fn.new { |dir|
var pd = 0
var longSeqs = [[2]]
var currSeq = [2]
for (i in 1...primes.count) {
var d = primes[i] - primes[i-1]
if ((dir == "ascending" && d <= pd) || (dir == "descending" && d >= pd)) {
if (currSeq.count > longSeqs[0].count) {
longSeqs = [currSeq]
} else if (currSeq.count == longSeqs[0].count) longSeqs.add(currSeq)
currSeq = [primes[i-1], primes[i]]
} else {
currSeq.add(primes[i])
}
pd = d
}
if (currSeq.count > longSeqs[0].count) {
longSeqs = [currSeq]
} else if (currSeq.count == longSeqs[0].count) longSeqs.add(currSeq)
System.print("Longest run(s) of primes with %(dir) differences is %(longSeqs[0].count):")
for (ls in longSeqs) {
var diffs = []
for (i in 1...ls.count) diffs.add(ls[i] - ls[i-1])
for (i in 0...ls.count-1) System.write("%(ls[i]) (%(diffs[i])) ")
System.print(ls[-1])
}
System.print()
}
System.print("For primes < 1 million:\n")
for (dir in ["ascending", "descending"]) longestSeq.call(dir)</lang>
{{out}}
<pre>
For primes < 1 million:
Longest run(s) of primes with ascending differences is 8:
128981 (2) 128983 (4) 128987 (6) 128993 (8) 129001 (10) 129011 (12) 129023 (14) 129037
402581 (2) 402583 (4) 402587 (6) 402593 (8) 402601 (12) 402613 (18) 402631 (60) 402691
665111 (2) 665113 (4) 665117 (6) 665123 (8) 665131 (10) 665141 (12) 665153 (24) 665177
Longest run(s) of primes with descending differences is 8:
322171 (22) 322193 (20) 322213 (16) 322229 (8) 322237 (6) 322243 (4) 322247 (2) 322249
752207 (44) 752251 (12) 752263 (10) 752273 (8) 752281 (6) 752287 (4) 752291 (2) 752293
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