A153521 Triangle T(n, k) = T(n-1, k) + T(n-1, k-1) + 11*T(n-2, k-1), read by rows.
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
Offset: 1
Examples
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;
Links
- G. C. Greubel, Rows n = 1..50 of the triangle, flattened
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).
Programs
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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
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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 *)
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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
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)
Extensions
Edited by G. C. Greubel, Mar 04 2021