A146315 Prime differences of primes subtracted from nearest square

2, 7, 11, 13, 23, 29, 31, 47, 53, 59, 61, 79, 83, 89, 97, 127, 131, 137, 139, 167, 173, 179, 191, 193, 223, 227, 233, 239, 251, 293, 307, 311, 313, 317, 359, 383, 389, 397, 439, 443, 461, 467, 479, 547, 557, 563, 569, 571, 647, 653, 659, 673, 727, 743, 761, 773

Offset

1,1

Comments

Terms in A146315 + A146316 produce a square

Links

Table of n, a(n) for n=1..56.

Formula

{p in A000040: A068527(p) in A000040}. - R. J. Mathar, Sep 26 2011

Example

a(6)=29 because when the prime 29 is subtracted from the square 36, the result is another prime, 7

Prog

(UBASIC) 10 'sq less pr are prime 20 N=1:O=1:C=1 30 A=3:S=sqrt(N) 40 B=N\A 50 if B*A=N then 120 60 A=A+2 70 if A<=S then 40 80 R=O^2:Q=R-N 90 if N<R and N=prmdiv(N) and Q=prmdiv(Q) then print R; N; Q:N=N+2:C=C+1:goto 30 100 if C>31 then stop 120 N=N+2:if N<R then 30:else O=O+1:goto 80

Crossrefs

Cf. A146316 - A146318.

Sequence in context: A027697 A364470 A235475 * A038892 A019346 A045369

Adjacent sequences: A146312 A146313 A146314 * A146316 A146317 A146318

Keyword

easy,nonn

Author

Enoch Haga, Oct 30 2008

Status

approved