A218491 Number of ways that prime(n) can be represented as the sum of four nonzero squares.

0, 0, 0, 1, 0, 1, 0, 1, 1, 0, 2, 2, 0, 2, 2, 1, 1, 2, 3, 2, 3, 3, 2, 1, 4, 1, 5, 2, 3, 2, 5, 2, 3, 4, 2, 5, 6, 6, 5, 3, 3, 5, 5, 6, 4, 7, 5, 9, 5, 7, 4, 6, 6, 5, 5, 7, 4, 9, 8, 4, 9, 6, 10, 8, 10, 7, 9, 9, 7, 9, 8, 9, 13, 10, 10, 11, 7, 13, 7, 10, 8, 11, 10, 13

Offset

1,11

Comments

a(pi(A213721(n))) = n, where pi(n) is the prime counting function.

Links

Arkadiusz Wesolowski, Table of n, a(n) for n = 1..1000

Index entries for sequences related to sums of squares

Example

a(11) = 2 because prime(11) = 31 = 2*1 + 4 + 25 = 4 + 3*9.

Mathematica

Table[Count[PowersRepresentations[Prime[n], 4, 2], _?(Min[#] > 0 &)], {n, 84}]

Crossrefs

Cf. A025428, A213721.

Sequence in context: A307757 A215283 A066518 * A111165 A349812 A029321

Adjacent sequences: A218488 A218489 A218490 * A218492 A218493 A218494

Keyword

nonn

Author

Arkadiusz Wesolowski, Nov 02 2012

Status

approved