A146316 Prime subtrahends of nearest squares producing prime differences

2, 2, 5, 3, 2, 7, 5, 2, 11, 5, 3, 2, 17, 11, 3, 17, 13, 7, 5, 2, 23, 17, 5, 3, 2, 29, 23, 17, 5, 31, 17, 13, 11, 7, 2, 17, 11, 3, 2, 41, 23, 17, 5, 29, 19, 13, 7, 5, 29, 23, 17, 3, 2, 41, 23, 11, 2, 47, 43, 41, 37, 23, 19, 17, 13, 53, 47, 41, 11, 5, 3, 2, 59, 53, 47, 5, 3, 2, 67, 59, 47, 37

Offset

1,1

Comments

Terms in A146315 + A146316 produce a square

Links

Table of n, a(n) for n=1..82.

Example

a(6)=7 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

A146315 A146317 A146318

Sequence in context: A132851 A361119 A293833 * A258803 A157495 A308143

Adjacent sequences: A146313 A146314 A146315 * A146317 A146318 A146319

Keyword

easy,nonn

Author

Enoch Haga, Oct 30 2008

Status

approved