login
A236542
Array T(n,k) read along descending antidiagonals: row n contains the primes with n steps in the prime index chain.
9
2, 7, 3, 13, 17, 5, 19, 41, 59, 11, 23, 67, 179, 277, 31, 29, 83, 331, 1063, 1787, 127, 37, 109, 431, 2221, 8527, 15299, 709, 43, 157, 599, 3001, 19577, 87803, 167449, 5381, 47, 191, 919, 4397, 27457, 219613, 1128889, 2269733, 52711
OFFSET
1,1
COMMENTS
Row n contains the primes A000040(j) for which A049076(j) = n.
FORMULA
T(1,k) = A007821(k).
T(n,k) = prime( T(n-1,k) ), n>1 .
EXAMPLE
The array starts:
2, 7, 13, 19, 23, 29, 37, 43, 47, 53,...
3, 17, 41, 67, 83, 109, 157, 191, 211, 241,...
5, 59, 179, 331, 431, 599, 919, 1153, 1297, 1523,...
11, 277, 1063, 2221, 3001, 4397, 7193, 9319,10631,12763,...
31, 1787, 8527,19577,27457,42043,72727,96797,112129,137077,...
MAPLE
A236542 := proc(n, k)
option remember ;
if n = 1 then
A007821(k) ;
else
ithprime(procname(n-1, k)) ;
end if:
end proc:
for d from 2 to 10 do
for k from d-1 to 1 by -1 do
printf("%d, ", A236542(d-k, k)) ;
end do:
end do:
MATHEMATICA
A007821 = Prime[Select[Range[15], !PrimeQ[#]&]];
T[n_, k_] := T[n, k] = If[n == 1, If[k <= Length[A007821], A007821[[k]], Print["A007821 must be extended"]; Abort[]], Prime[T[n-1, k]]];
Table[T[n-k+1, k], {n, 1, 9}, {k, n, 1, -1}] // Flatten (* Jean-François Alcover, Apr 16 2020 *)
CROSSREFS
Cf. A007821 (row 1), A049078 (row 2), A049079 (row 3), A007097 (column 1), A058010 (diagonal), A057456 - A057457 (columns), A135044, A236536.
Sequence in context: A056756 A120861 A354368 * A279357 A099130 A362359
KEYWORD
nonn,tabl
AUTHOR
R. J. Mathar, Jan 28 2014
STATUS
approved