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.

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A159977 a(n) = (smallest prime >= Fibonacci(n)) - Fibonacci(n).

Original entry on oeis.org

1, 1, 0, 0, 0, 3, 0, 2, 3, 4, 0, 5, 0, 2, 3, 4, 0, 7, 20, 14, 3, 2, 0, 13, 4, 10, 11, 16, 0, 23, 4, 4, 25, 10, 14, 35, 6, 24, 3, 2, 6, 7, 0, 20, 9, 48, 0, 5, 28, 18, 23, 14, 14, 11, 16, 10, 21, 4, 62, 13, 38, 12, 7, 16, 12, 19, 36, 28, 143, 32, 58, 29, 96, 100, 33, 2, 30, 27, 12, 62, 25, 46, 0
Offset: 1

Views

Author

Enoch Haga, Apr 28 2009

Keywords

Examples

			a(1) = a(2) = 1 because Fibonacci(1) = Fibonacci(2) = 1, the smallest prime >= 1 is 2, and 2 - 1 = 1.
a(3) = a(4) = a(5) = 0 because Fibonacci(3)=2, Fibonacci(4)=3, and Fibonacci(5)=5 are all prime.
		

Crossrefs

Programs

  • Maple
    a:= n-> (f-> nextprime(f-1)-f)(combinat[fibonacci](n)):
    seq(a(n), n=1..100);  # Alois P. Heinz, Feb 04 2018
  • Mathematica
    Table[If[PrimeQ[n],0,NextPrime[n]-n],{n,Fibonacci[Range[90]]}] (* Harvey P. Dale, Jul 22 2016 *)
  • PARI
    F=1;G=0;for(i=1,100,print1(nextprime(F)-F,",");T=F;F+=G;G=T) \\ Hagen von Eitzen, Jul 20 2009
  • UBASIC
    10 'FiboA 20 A=1:print A; 30 B=1:print B; 40 C=A+B:print C;:T=T+1 41 if C<>prmdiv(C) then print "<";nxtprm(C)-C;">":else print "<";0;">"; 50 D=B+C:print D; 51 if D<>prmdiv(D) then print "<";nxtprm(D)-D;">":else print "<";0;">"; 60 A=C:B=D:if T>22 then stop:else 40
    

Formula

a(n) = (smallest prime >= Fibonacci(n)) - Fibonacci(n).
a(n) = 0 <=> n in { A001605 }. - Alois P. Heinz, Feb 04 2018

Extensions

More terms (cf. b-file) from Hagen von Eitzen, Jul 20 2009
Edited by Jon E. Schoenfield, Feb 04 2018

A375751 a(n) is the difference between F=A000045(n) and the largest prime not exceeding F.

Original entry on oeis.org

0, 0, 0, 1, 0, 2, 3, 2, 0, 5, 0, 4, 3, 4, 0, 5, 4, 2, 7, 4, 0, 17, 8, 14, 31, 14, 0, 37, 20, 26, 9, 20, 22, 11, 6, 12, 15, 32, 18, 17, 0, 16, 43, 24, 0, 17, 20, 26, 27, 20, 6, 9, 12, 34, 29, 36, 30, 47, 48, 4, 45, 32, 54, 27, 132, 22, 31, 4, 32, 11, 12, 60, 7, 76
Offset: 3

Views

Author

Hugo Pfoertner, Aug 27 2024

Keywords

Crossrefs

Programs

  • Maple
    a:= n-> (F-> F-prevprime(F+1))(combinat[fibonacci](n)):
    seq(a(n), n=3..76);  # Alois P. Heinz, Aug 27 2024
  • Mathematica
    a[n_]:=Module[{p=2},While[(f=Fibonacci[n])>=p, pold=p;p=NextPrime[p]]; d=f-pold;If[d>0,f-pold,d=0]; d]; Array[a,74,3] (* Stefano Spezia, Aug 27 2024 *)
    Map[(# - NextPrime[# + 1, -1]) &, Fibonacci[Range[3, 76]]] (* Amiram Eldar, Aug 29 2024 *)
  • PARI
    a(n) = my(F=fibonacci(n)); F-precprime(F)
    
  • Python
    from sympy import prevprime, fibonacci
    def A375753(n): return (F:=fibonacci(n)) - prevprime(F+1) # Karl-Heinz Hofmann, Aug 27 2024

Formula

a(n) = A000045(n) - A138184(n).
a(n) = 0 <=> n in { A001605 }. - Alois P. Heinz, Aug 27 2024
Showing 1-2 of 2 results.