cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

Showing 1-4 of 4 results.

A146318 Prime subtrahends of nearest cubes producing prime differences.

Original entry on oeis.org

3, 5, 41, 47, 53, 59, 61, 127, 137, 149, 157, 163, 173, 179, 193, 197, 199, 211, 349, 373, 409, 433, 439, 499, 509, 727, 743, 761, 773, 809, 821, 827, 863, 887, 911, 929, 941, 947, 953, 971, 977, 983, 997, 1361, 1381, 1447, 1451, 1459, 1471, 1487, 1489, 1499
Offset: 1

Views

Author

Enoch Haga, Oct 30 2008

Keywords

Comments

Terms in A146317 + A146318 produce a cube

Examples

			a(3)=41 because when the prime 23 is subtracted from the cube 64, the result is another prime, 41
		

Crossrefs

Programs

  • UBASIC
    10 'cu less pr are prime 20 N=1:O=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^3:Q=R-N 90 if N
    				

A146316 Prime subtrahends of nearest squares producing prime differences.

Original entry on oeis.org

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

Views

Author

Enoch Haga, Oct 30 2008

Keywords

Comments

Terms in A146315 + A146316 produce a square

Examples

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

Crossrefs

Programs

  • 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 N31 then stop 120 N=N+2:if N
    				

A146317 Prime differences of primes subtracted from nearest cube.

Original entry on oeis.org

5, 3, 23, 17, 11, 5, 3, 89, 79, 67, 59, 53, 43, 37, 23, 19, 17, 5, 163, 139, 103, 79, 73, 13, 3, 2, 257, 239, 227, 191, 179, 173, 137, 113, 89, 71, 59, 53, 47, 29, 23, 17, 3, 367, 347, 281, 277, 269, 257, 241, 239, 229, 197, 179, 157, 149, 131, 127, 109, 107, 101, 71, 61
Offset: 1

Views

Author

Enoch Haga, Oct 30 2008

Keywords

Comments

Terms in A146317 + A146318 produce a cube

Examples

			a(3)=23 because when the prime 23 is subtracted from the cube 64, the result is another prime, 41
		

Crossrefs

Programs

  • Maple
    R:= NULL: count:= 0: p:= 1:
    while count < 100 do
      p:= nextprime(p);
      d:= ceil(p^(1/3))^3-p;
      if isprime(d) then count:= count+1; R:= R, d fi;
    od:
    R; # Robert Israel, Aug 06 2019
  • UBASIC
    10 'cu less pr are prime 20 N=1:O=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^3:Q=R-N 90 if N
    				

A146757 Number of primes p < 10^n such that s - p is prime, where s is the next square greater than p.

Original entry on oeis.org

2, 15, 68, 363, 2084, 13567, 95164, 705036, 5444255, 43211106, 351904307, 2921904565
Offset: 1

Views

Author

Enoch Haga, Nov 02 2008

Keywords

Comments

The number of primes p in the range 2 <= p <= 10^n for which The distance to the next larger square (A068527(p)) is also a prime. - R. J. Mathar, Sep 26 2011

Examples

			A(2) = 15 because at 10^2 there are 15 primes that, subtracted from the next higher value square, produce prime differences: {2, 7, 11, 13, 23, 29, 31, 47, 53, 59, 61, 79, 83, 89, 97}.
		

Crossrefs

Programs

  • Mathematica
    Table[Length[Select[Prime[Range[PrimePi[10^n]]], PrimeQ[Ceiling[Sqrt[#]]^2 - #] &]], {n, 6}] (* T. D. Noe, Mar 31 2013 *)
  • UBASIC
    10 'sq less pr are prime 20 N=1:O=1:C=1 30 A=3:S=sqrt(N):if N>10^3 then print N,C-1:stop 40 B=N\A 50 if B*A=N then 100 60 A=A+2 70 if A<=S then 40 80 R=O^2:Q=R-N 90 if N1 print R;N;Q;C:N=N+2:C=C+1:goto 30 100 N=N+2:if N
    				

Extensions

Name clarified by T. D. Noe, Mar 31 2013
a(8)-a(12) from Chai Wah Wu, Jun 22 2019
Showing 1-4 of 4 results.