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.

A178837 Indices k such that the sum of the digits of Fibonacci(k) is a prime number.

Original entry on oeis.org

3, 4, 5, 8, 9, 11, 14, 15, 18, 22, 25, 26, 27, 29, 30, 31, 34, 39, 41, 43, 45, 47, 51, 53, 54, 58, 61, 63, 65, 66, 67, 81, 85, 87, 90, 94, 99, 105, 107, 111, 113, 118, 122, 133, 135, 139, 147, 149, 151, 161, 167, 169, 173, 187, 191, 193, 194, 195, 198, 202, 213, 223
Offset: 1

Views

Author

Michel Lagneau, Jun 17 2010

Keywords

Examples

			3 is in the sequence because Fibonacci(3) = 2, and 2 is prime.
113 is in the sequence because Fibonacci(113) = 184551825793033096366333 and the sum of the digits = 103 is prime.
		

Crossrefs

Programs

  • Maple
    with(combinat, fibonacci):nn:= 120: for n from 1 to 700 do:p:=fibonacci(n):l:=length(p):n0:=p:s:=0:for m from 1 to l do:q:=n0:u:=irem(q, 10):v:=iquo(q, 10):n0:=v :s:=s+u:od:if type(s, prime)=true then printf(`%d, `, n): else fi:od:
    # second Maple program:
    q:= n-> isprime(add(i, i=convert(combinat[fibonacci](n), base, 10))):
    select(q, [$0..223])[];  # Alois P. Heinz, Jul 15 2025
  • Mathematica
    Select[Range[300],PrimeQ[Total[IntegerDigits[Fibonacci[#]]]]&] (* Harvey P. Dale, Oct 22 2017 *)

A111331 Prime Fibonacci numbers whose digits in base 10 sum up to a prime.

Original entry on oeis.org

2, 3, 5, 89, 514229, 433494437, 2971215073, 3061719992484545030554313848083717208111285432353738497131674799321571238149015933442805665949
Offset: 1

Views

Author

Stefan Steinerberger, Nov 05 2005

Keywords

Comments

Fibonacci(104911) is the next (probable) prime whose digits sum to a prime. Thus the next term would be 21925 digits long. - Hans Havermann, Nov 06 2005

Examples

			514229 is a prime Fibonacci number and the sum of the digits 5 + 1 + 4 + 2 + 2 + 9 = 23 is also a prime.
		

Crossrefs

Programs

  • Mathematica
    Select[Fibonacci[Range[1000]],PrimeQ[#]&&PrimeQ[Total[IntegerDigits[#]]]&] (* James C. McMahon, May 31 2024 *)

A181364 Fibonacci numbers whose digits, when squared, sum to a prime.

Original entry on oeis.org

21, 377, 610, 2584, 17711, 75025, 196418, 514229, 63245986, 701408733, 1134903170, 1836311903, 2971215073, 17167680177565, 72723460248141, 117669030460994, 2880067194370816120, 19740274219868223167, 354224848179261915075, 1500520536206896083277
Offset: 1

Views

Author

Carmine Suriano, Oct 15 2010

Keywords

Examples

			a(5) = 17711 = Fibonacci(22) since 1^2+7^2+7^2+1^2+1^2 = 1+49+49+1+1 = 101 is prime.
		

Crossrefs

Intersection of A000045 and A108662.

Programs

  • Mathematica
    Select[Fibonacci[Range[150]],PrimeQ[Total[IntegerDigits[#]^2]]&] (* Harvey P. Dale, Feb 27 2012 *)

Formula

a(n) = A000045(A178838(n)). - Michel Marcus, Sep 01 2025

Extensions

Corrected and extended by Harvey P. Dale, Feb 27 2012

A316527 Fibonacci numbers whose sum of digits is not a prime.

Original entry on oeis.org

0, 1, 8, 13, 55, 144, 233, 987, 1597, 4181, 6765, 10946, 28657, 46368, 317811, 2178309, 3524578, 9227465, 14930352, 24157817, 39088169, 102334155, 267914296, 701408733, 1836311903, 4807526976, 7778742049, 12586269025, 32951280099, 139583862445, 225851433717
Offset: 1

Views

Author

Vincenzo Librandi, Jul 11 2018

Keywords

Crossrefs

Complement of A065398 within A000045.
Cf. A178837.

Programs

  • GAP
    S:=List(List(List([2..60],Fibonacci),ListOfDigits),Sum);;
    a:=[];; for i in [1..Length(S)] do if not IsPrime(S[i]) then Add(a,Fibonacci(i+1)); fi; od; a:=Concatenation([0],a); # Muniru A Asiru, Jul 12 2018
  • Magma
    [Fibonacci(n): n in [2..80] | not IsPrime(&+Intseq(Fibonacci(n)))];
    
  • Mathematica
    Rest[Select[Fibonacci[Range[100]], !PrimeQ[Total[IntegerDigits[#]]]&]]
Showing 1-4 of 4 results.