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A193934 Triangle read by rows: row n gives the n primes corresponding to A187822. 0
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 (list; table; graph; refs; listen; history; text; internal format)
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

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Last modified September 23 12:43 EDT 2021. Contains 347617 sequences. (Running on oeis4.)