A218536 1^2 * 3^2 * 5^2 * ... * (p-4)^2 * (p-2)^2 where p is the n-th prime number (n >= 2).

1, 9, 225, 893025, 108056025, 4108830350625, 1187451971330625, 21004837920867425625, 4132819745225119839515625, 3475701405734325785032640625, 454631398596176852476116706640625, 5601513462103494999358233942519140625, 9416144129795975093921191257374675390625

Offset

2,2

Comments

Subsequence of A001818.

a(n) is congruent to 1 or -1 (modulo the n-th prime).

References

Kenneth Rosen, Elementary Number Theory and its Applications, Addison Wesley, page 223.

Links

Table of n, a(n) for n=2..14.

Example

a(4)= 225 because the 4th prime number is 7 and 1^2*3^2*5^2 = 225.  225 is congruent to 1 (mod 7).

Mathematica

Table[Product[(Prime[n] - 2i)^2, {i, n}], {n, 2, 15}]

Crossrefs

Sequence in context: A138564 A285985 A330830 * A338377 A211048 A327146

Adjacent sequences: A218533 A218534 A218535 * A218537 A218538 A218539

Keyword

nonn

Author

Geoffrey Critzer, Nov 01 2012

Status

approved