A086284 Number of prime squares with maximum integer n (see comment for definition).

1, 3, 5, 11, 14, 21, 29, 37, 56, 88, 110, 145, 171, 197, 241, 302, 347, 392, 438, 484, 555, 650, 717, 806, 916, 1026, 1180, 1334, 1451, 1600, 1765, 1930, 2101, 2315, 2539, 2816, 3108, 3400, 3702, 4063

Offset

1,2

Comments

A prime square is constructed by drawing a square and placing a positive integer at each corner. All adjacent corners must sum to a prime. The maximum integer is the largest integer that may be used.

Links

Table of n, a(n) for n=1..40.

Example

a(4)=11 since we have the 2 X 2 squares:
11 21 21 32 32 41 43 43 43 43 41
11 11 12 21 23 14 14 34 12 32 12

Prog

(PARI) { ps(n)=local(s); s=2; forstep (i1=1, n, 2, forstep (i2=2, n, 2, forstep (i3=i1, n, 2, forstep (i4=i2, n, 2, if (isprime(i1+i2) && isprime(i2+i3) && isprime(i3+i4) && isprime(i4+i1), s++))))); if (n==1, s=1); if (n==2, s=3); s } for (i=1, 40, print1(ps(i)", "))

Crossrefs

Sequence in context: A058595 A154773 A176658 * A136500 A024897 A048702

Adjacent sequences: A086281 A086282 A086283 * A086285 A086286 A086287

Keyword

nonn

Author

Jon Perry, Aug 28 2003

Status

approved