A367942 -id:A367942 - cp's OEIS frontend

A367944 a(n) = Product_{i=1..n, j=1..n} (i^2 + 5*j^2).

1, 6, 27216, 1344924798336, 3605580335899213007486976, 1648055031941075082958467426002632704000000, 312704667066499295437237787452750428210311485710262201221120000000

Offset: 0

Vaclav Kotesovec, Dec 05 2023

nonn

In general, for d>0, Product_{i=1..n, j=1..n} (i^2 + d*j^2) ~ c(d) * n^(2*n^2 - 1/2) * (d+1)^(n*(n+1)) * d^(-n/2) * exp(n*(n+1)*(Pi*d/2 - (d-1)*arctan(sqrt(d))) / sqrt(d) - 3*n^2), where c(d) is a constant (dependent only on d).

c(1) = exp(Pi/12) * Gamma(1/4) / (2*Pi)^(5/4), cf. A324403.

Cf. A324403 (d=1), A367941 (d=2), A367942 (d=3), A367943 (d=4).

Cf. A367542, A367543, A367958.

Table[Product[i^2+5*j^2, {i, 1, n}, {j, 1, n}], {n, 0, 8}]

a(n) ~ c * n^(2*n^2 - 1/2) * 6^(n*(n+1)) * 5^(-n/2) * exp(n*(n+1)*(5*Pi/2 - 4*arctan(sqrt(5)))/sqrt(5) - 3*n^2), where c = 0.4431081869167792949266065295798218232844989957987096447783995373751372668...

A367941 a(n) = Product_{i=1..n, j=1..n} (i^2 + 2*j^2).

Original entry on oeis.org

1, 3, 1944, 4102777008, 140890630179993255936, 247470977313135626800897828778803200, 54132901224855040835735917614114353691165557521593139200

Offset: 0

Vaclav Kotesovec, Dec 05 2023

nonn

Cf. A324403, A367942, A367943, A367944.

Cf. A367542, A367543.

Table[Product[i^2+2*j^2, {i, 1, n}, {j, 1, n}], {n, 0, 8}]

a(n) ~ c * n^(2*n^2 - 1/2) * 3^(n*(n+1)) * 2^(-n/2) * exp(n*(n+1)*(Pi - arctan(sqrt(2))) / sqrt(2) - 3*n^2) , where c = 0.4690673220228472212446336926899602910226601891141458824921925169726804439...

A367943 a(n) = Product_{i=1..n, j=1..n} (i^2 + 4*j^2).

Original entry on oeis.org

1, 5, 13600, 294372000000, 252880261890048000000000, 27099784799070466617992871936000000000000, 882065676199020188908312950703217787436793856000000000000000000

Offset: 0

Vaclav Kotesovec, Dec 05 2023

nonn

Cf. A324403, A367941, A367942, A367944.

Cf. A367542, A367543.

Table[Product[i^2+4*j^2, {i, 1, n}, {j, 1, n}], {n, 0, 8}]

a(n) ~ c * n^(2*n^2 - 1/2) * 5^(n*(n+1)) * 2^(-n) * exp(n*(n+1)*(2*Pi - 3*arctan(2))/2 - 3*n^2) , where c = 0.4523180383519335764034720087114905921141637339852374451758854101884791581...

cp's OEIS Frontend

A367944 a(n) = Product_{i=1..n, j=1..n} (i^2 + 5*j^2).

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A367941 a(n) = Product_{i=1..n, j=1..n} (i^2 + 2*j^2).

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Programs

Mathematica

Formula

A367943 a(n) = Product_{i=1..n, j=1..n} (i^2 + 4*j^2).

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Author

Keywords

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Mathematica

Formula