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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 (list; table; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Row n contains the primes A000040(j) for which A049076(j) = n.

LINKS

Table of n, a(n) for n=1..45.

N. Fernandez, An order of primeness, F(p).

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-Fran├žois 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: A256448 A056756 A120861 * A279357 A099130 A076992

Adjacent sequences:  A236539 A236540 A236541 * A236543 A236544 A236545

KEYWORD

nonn,tabl

AUTHOR

R. J. Mathar, Jan 28 2014

STATUS

approved

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Last modified October 19 22:05 EDT 2021. Contains 348095 sequences. (Running on oeis4.)