A193934 Triangle read by rows: row n gives the n primes corresponding to A187822.

3, 3, 7, 3, 7, 31, 3, 7, 31, 127, 3, 7, 19, 29, 43, 3, 7, 41, 61, 83, 167, 3, 7, 19, 29, 43, 151, 271, 3, 11, 17, 53, 163, 409, 1109, 1439, 3, 61, 79, 103, 283, 1171, 1459, 3187, 4339, 3, 7, 19, 29, 43, 163, 233, 307, 1039, 1409, 3, 29, 59, 71, 233, 269, 353

Offset

1,1

Links

Table of n, a(n) for n=1..62.

Example

Triangle begins:
n = 1 and k = 2  ->    [3]
n = 2 and k = 4  ->    [3, 7]
n = 3 and k = 16 ->   [3, 7, 31]
n = 4 and k = 64 ->   [3, 7, 31, 127]
n = 5 and k = 140 -> [3, 7, 19, 29, 43]
n = 6 and k = 440 -> [3, 7, 41, 61, 83, 167]
…
The sequence A187822 gives the values k.

Maple

with(numtheory):for n from 0 to 30
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 1 to n1 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={2}; Do[ lst=Union[lst , {Prime[i]}], {i, 1, 5000}]; a[n_]:=Catch[For[k=1, True, k++, cnt=Count[Accumulate[Divisors[k]], _?PrimeQ]; If[cnt==n, Print[Intersection[Accumulate[Divisors[k]], lst]]; Throw[k]]]]; Table[a[n], {n, 0, 15}]

Crossrefs

Cf. A187822.

Sequence in context: A159913 A183061 A172097 * A030316 A208884 A034257

Adjacent sequences: A193931 A193932 A193933 * A193935 A193936 A193937

Keyword

nonn,tabl

Author

Michel Lagneau, Jan 02 2013

Status

approved