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A153521 Triangle T(n, k) = T(n-1, k) + T(n-1, k-1) + 11*T(n-2, k-1), read by rows. 15
2, 11, 11, 2, 238, 2, 2, 1329, 1329, 2, 2, 1353, 5276, 1353, 2, 2, 1377, 21248, 21248, 1377, 2, 2, 1401, 37508, 100532, 37508, 1401, 2, 2, 1425, 54056, 371768, 371768, 54056, 1425, 2, 2, 1449, 70892, 838412, 1849388, 838412, 70892, 1449, 2, 2, 1473, 88016, 1503920, 6777248, 6777248, 1503920, 88016, 1473, 2 (list; table; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

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

FORMULA

T(n, k)= T(n-1, k) + T(n-1, k-1) + 11*T(n-2, k-1).

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

T(n,k,p,q,j) = T(n-1,k,p,q,j) + T(n-1,k-1,p,q,j) + (p*j+q)*prime(j)*T(n-2,k-1,p,q,j) with T(2,k,p,q,j) = prime(j), T(3,2,p,q,j) = 2*prime(j)^2 -4, T(4,2,p,q,j) = T(4,3,p,q,j) = prime(j)^2 -2, T(n,1,p,q,j) = T(n,n,p,q,j) = 2 and (p,q,j) = (0,1,5).

Sum_{k=1..n} T(n,k,p,q,j) = 2*(prime(j)-3)*[n=1] -2*prime(j)*(prime(j)-3)*[n=2] +2*prime(j)^2*(i*sqrt(prime(j)))^(n-3)*(ChebyshevU(n-3, -i/Sqrt(prime(j))) -((prime(j) -2)*i/sqrt(prime(j)))*ChebyshevU(n-4, -i/sqrt(prime(j)))) for (p,q,j)=(0,1,5) = A151617(n).

Row sums satisfy the recurrence relation S(n) = 2*S(n-1) + prime(j)*S(n-2), for n > 4, with S(1) = 2, S(2) = 2*prime(j), S(3) = 2*prime(j)^2, S(4) = 2*prime(j)^3 for j=5. (End)

EXAMPLE

Triangle begins as:

   2;

  11,   11;

   2,  238,     2;

   2, 1329,  1329,       2;

   2, 1353,  5276,    1353,       2;

   2, 1377, 21248,   21248,    1377,       2;

   2, 1401, 37508,  100532,   37508,    1401,       2;

   2, 1425, 54056,  371768,  371768,   54056,    1425,     2;

   2, 1449, 70892,  838412, 1849388,  838412,   70892,  1449,    2;

   2, 1473, 88016, 1503920, 6777248, 6777248, 1503920, 88016, 1473, 2;

MATHEMATICA

T[n_, k_, p_, q_, j_]:= T[n, k, p, q, 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, p, q, j] + T[n-1, k-1, p, q, j] + (p*j+q)*Prime[j]*T[n-2, k-1, p, q, j] ]]];

Table[T[n, k, 0, 1, 5], {n, 12}, {k, n}]//Flatten (* modified by G. C. Greubel, Mar 04 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, p, q, 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, p, q, j) + T(n-1, k-1, p, q, j) + (p*j+q)*nth_prime(j)*T(n-2, k-1, p, q, j)

flatten([[T(n, k, 0, 1, 5) for k in (1..n)] for n in (1..12)]) # G. C. Greubel, Mar 04 2021

(Magma)

f:= func< n, j | Round(((3-(-1)^n)/2)*NthPrime(j)^(n-1) - 2^((3-(-1)^n)/2)) >;

function T(n, k, p, q, 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, p, q, j) + T(n-1, k-1, p, q, j) + (p*j+q)*NthPrime(j)*T(n-2, k-1, p, q, j);

  end if; return T;

end function;

[T(n, k, 0, 1, 5): k in [1..n], n in [1..12]]; // G. C. Greubel, Mar 04 2021

CROSSREFS

Sequences with variable (p,q,j): A153516 (0,1,2), A153518 (0,1,3), A153520 (0,1,4), this sequence (0,1,5), A153648 (1,0,3), A153649 (1,1,4), A153650 (1,4,5), A153651 (1,5,6), A153652 (2,1,7), A153653 (2,1,8), A153654 (2,1,9), A153655 (2,1,10), A153656 (2,3,9), A153657 (2,7,10).

Cf. A151617 (row sums).

Sequence in context: A163344 A064743 A109868 * A153650 A338049 A256665

Adjacent sequences:  A153518 A153519 A153520 * A153522 A153523 A153524

KEYWORD

nonn,tabl,easy,less

AUTHOR

Roger L. Bagula, Dec 28 2008

EXTENSIONS

Edited by G. C. Greubel, Mar 04 2021

STATUS

approved

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Last modified June 18 22:00 EDT 2021. Contains 345125 sequences. (Running on oeis4.)