A153654 Triangle T(n, k, j) = T(n-1, k, j) + T(n-1, k-1, j) + (2*j + 1)*prime(j)*T(n-2, k-1, j) with T(2, k, j) = prime(j) and j = 9, read by rows.

2, 23, 23, 2, 1054, 2, 2, 12165, 12165, 2, 2, 13041, 484928, 13041, 2, 2, 13917, 5814074, 5814074, 13917, 2, 2, 14793, 11526908, 223541684, 11526908, 14793, 2, 2, 15669, 17623430, 2775818930, 2775818930, 17623430, 15669, 2, 2, 16545, 24103640, 7830701156, 103239353768, 7830701156, 24103640, 16545, 2

Offset

1,1

Links

G. C. Greubel, Rows n = 1..50 of the triangle, flattened

Formula

T(n, k, j) = T(n-1, k, j) + T(n-1, k-1, j) + (2*j + 1)*prime(j)*T(n-2, k-1, j) with T(2, k, j) = prime(j), T(3, 2, j) = 2*prime(j)^2 - 4, T(4, 2, j) = T(4, 3, j) = prime(j)^2 - 2, T(n, 1, j) = T(n, n, j) = 2 and j = 9.

From G. C. Greubel, Mar 04 2021: (Start)

Sum_{k=0..n} T(n, k, 10) = -(68/361)*[n=0] - (92/19)*[n=1] + 1058*(i*sqrt(437))^(n-2)*(ChebyshevU(n-2, -i/sqrt(437)) - (21*i/sqrt(437))*ChebyshevU(n-3, -i/sqrt(437) )).

Row sums satisfy the recurrence S(n) = 2*S(n-1) + 437*S(n-2) for n>4 with S(0) = 2, S(1) = 46, S(2) = 1058, S(3) = 24334. (End)

Example

Triangle begins as:
   2;
  23,    23;
   2,  1054,        2;
   2, 12165,    12165,          2;
   2, 13041,   484928,      13041,            2;
   2, 13917,  5814074,    5814074,        13917,          2;
   2, 14793, 11526908,  223541684,     11526908,      14793,        2;
   2, 15669, 17623430, 2775818930,   2775818930,   17623430,    15669,     2;
   2, 16545, 24103640, 7830701156, 103239353768, 7830701156, 24103640, 16545, 2;

Mathematica

T[n_, k_, j_]:= T[n, k, j]= If[n==2, Prime[j], If[n==3 && k==2 || n==4 && 2<=k<=3, ((3-(-1)^n)/2)*Prime[j]^(n-1) -2^((3-(-1)^n)/2), If[k==1 || k==n, 2, T[n-1, k, j] + T[n-1, k-1, j] + (2*j+1)*Prime[j]*T[n-2, k-1, j] ]]];
Table[T[n, k, 9], {n, 12}, {k, n}]//Flatten (* modified by G. C. Greubel, Mar 03 2021 *)

Prog

(Sage)
@CachedFunction
def f(n, j): return ((3-(-1)^n)/2)*nth_prime(j)^(n-1) - 2^((3-(-1)^n)/2)
def T(n, k, j):
    if (n==2): return nth_prime(j)
    elif (n==3 and k==2 or n==4 and 2<=k<=3): return f(n, j)
    elif (k==1 or k==n): return 2
    else: return T(n-1, k, j) + T(n-1, k-1, j) + (2*j+1)*nth_prime(j)*T(n-2, k-1, j)
flatten([[T(n, k, 9) for k in (1..n)] for n in (1..12)]) # G. C. Greubel, Mar 03 2021
(Magma)
f:= func< n, j | Round(((3-(-1)^n)/2)*NthPrime(j)^(n-1) - 2^((3-(-1)^n)/2)) >;
function T(n, k, j)
  if n eq 2 then return NthPrime(j);
  elif (n eq 3 and k eq 2 or n eq 4 and k eq 2 or n eq 4 and k eq 3) then return f(n, j);
  elif (k eq 1 or k eq n) then return 2;
  else return T(n-1, k, j) + T(n-1, k-1, j) + (2*j+1)*NthPrime(j)*T(n-2, k-1, j);
  end if; return T;
end function;
[T(n, k, 9): k in [1..n], n in [1..12]]; // G. C. Greubel, Mar 03 2021

Crossrefs

Cf. A153652 (j=7), A153653 (j=8), this sequence (j=9), A153655 (j=10).

Cf. A153516, A153518, A153520, A153521, A153648, A153649, A153650, A153651, A153656, A153657.

Sequence in context: A158992 A128365 A326954 * A153656 A242037 A233692

Adjacent sequences: A153651 A153652 A153653 * A153655 A153656 A153657

Keyword

nonn,tabl,easy,less

Author

Roger L. Bagula, Dec 30 2008

Extensions

Edited by G. C. Greubel, Mar 03 2021

Status

approved