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A195258 Triangle read by rows: row n gives the n primes corresponding to A187825. 0
3, 2, 3, 293, 307, 317, 1373, 1451, 1481, 1487, 6947, 7109, 7331, 7349, 7411, 7173, 8423, 8467, 8681, 8693, 8713, 6221, 6269, 6311, 6379, 6521, 6529, 6551, 44221, 48497, 49307, 50111, 50177, 50497, 50527, 50543, 14813, 14891, 14957, 15053, 15161, 15187, 15227 (list; table; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..43.

EXAMPLE

Triangle begins:

n = 1 and k = 3  ->   [3]

n = 2 and k = 2  ->   [2, 3]

n = 3 and k = 140 -> [293, 307, 317]

n = 4 and k = 560 -> [1373, 1451, 1481, 1487]

The sequence A187825 gives the values k.

MAPLE

with(numtheory):for n from 0 to 12

do:ii:=0:for k from 1 to 4000000 while(ii=0) do:s:=0:x:=divisors(k):n1:=nops(x):it:=0:lst:={}: for a from n1 by -1 to 1 do:s:=s+x[a]:if type(s, prime)=true then it:=it+1:lst:=lst union {s}:else fi:od: if it = n then ii:=1: print(lst) :else fi:od:od:

MATHEMATICA

lst={}; Do[lst=Union[lst, {Prime[i]}], {i, 1, 5000}]; a[n_]:=Catch[For[k=1, True, k++, cnt=Count[Accumulate[Divisors[k]//Reverse], _?PrimeQ]; If[cnt==n, Print[Intersection[Accumulate[Divisors[k]//Reverse], lst]]; Throw[k]]]]; Table[a[n], {n, 0, 10}]

CROSSREFS

Cf. A187825.

Sequence in context: A109591 A143932 A304496 * A070471 A070690 A160387

Adjacent sequences:  A195255 A195256 A195257 * A195259 A195260 A195261

KEYWORD

nonn,tabl

AUTHOR

Michel Lagneau, Jan 02 2013

STATUS

approved

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Last modified May 24 03:05 EDT 2022. Contains 354005 sequences. (Running on oeis4.)