A195258 Triangle read by rows: row n gives the n primes corresponding to A187825.

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

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 * A370450 A070471 A070690

Adjacent sequences: A195255 A195256 A195257 * A195259 A195260 A195261

Keyword

nonn,tabl

Author

Michel Lagneau, Jan 02 2013

Status

approved