A178837 -id:A178837 - cp's OEIS frontend

A065398 Fibonacci numbers whose digits sum to a prime.

2, 3, 5, 21, 34, 89, 377, 610, 2584, 17711, 75025, 121393, 196418, 514229, 832040, 1346269, 5702887, 63245986, 165580141, 433494437, 1134903170, 2971215073, 20365011074, 53316291173, 86267571272, 591286729879, 2504730781961

Offset: 1

Jason Earls, Nov 22 2001

Harry J. Smith, Table of n, a(n) for n = 1..100

Cf. A000045, A178837 (corresponding indices).

Select[Fibonacci[Range[100]],PrimeQ[Total[IntegerDigits[#]]]&] (* Harvey P. Dale, Mar 24 2017 *)

{ for (m=1, 10^2, my(f=fibonacci(m)); if (isprime(sumdigits(f)), print1(f, ", "))) } \\ Harry J. Smith, Oct 18 2009

a(n) = A000045(A178837(n)).

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

Vincenzo Librandi, Jul 11 2018

Complement of A065398 within A000045.

Cf. A178837.

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

[Fibonacci(n): n in [2..80] | not IsPrime(&+Intseq(Fibonacci(n)))];

Rest[Select[Fibonacci[Range[100]], !PrimeQ[Total[IntegerDigits[#]]]&]]

A383045 Integers k for which the sum of digits of Fibonacci(k) is a Fibonacci number.

Original entry on oeis.org

0, 1, 2, 3, 4, 5, 6, 8, 13, 28, 33, 49, 85, 94, 107, 286, 299, 366, 421, 422, 443, 657, 2807, 4483, 4531, 18694, 49140, 79033, 79850, 80290, 128306, 129049, 129618, 208245, 338888, 546571, 882766, 883822, 886342

Offset: 1

Michel Marcus, Apr 14 2025

			Fibonacci(8) = 21 and sumdigits(21) = 3, a Fibonacci number, so 8 is a term.

Cf. A000045, A020995, A067515, A004090, A178837, A382053.

q:= n-> (t-> issqr(t+4) or issqr(t-4))(5*add(i, i=convert(combinat[fibonacci](n), base, 10))^2):
select(q, [$0..4600])[];  # Alois P. Heinz, Jul 15 2025

fibQ[n_] := Or @@ IntegerQ /@ Sqrt[5*n^2 + {-4, 4}]; Select[Range[0, 1000], fibQ[DigitSum[Fibonacci[#]]] &] (* Amiram Eldar, Apr 14 2025 *)

isfib(n) = my(k=n^2); k+=(k+1)<<2; issquare(k) || (n>0 && issquare(k-8));
isok(k) = isfib(sumdigits(fibonacci(k)));

a(36)-a(39) from Amiram Eldar, Apr 14 2025

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A065398 Fibonacci numbers whose digits sum to a prime.

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

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A383045 Integers k for which the sum of digits of Fibonacci(k) is a Fibonacci number.

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