login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A270475 Integers n such that A003266(n) is not divisible by n*(n+1)/2. 1
2, 3, 4, 6, 7, 22, 23, 42, 43, 66, 67, 82, 83, 102, 103, 126, 127, 162, 163, 166, 167, 222, 223, 226, 227, 282, 283, 366, 367, 382, 383, 442, 443, 462, 463, 466, 467, 486, 487, 502, 503, 522, 523, 546, 547, 586, 587, 606, 607, 642, 643, 646, 647, 682, 683, 726, 727, 786, 787 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

This sequence contains primes dividing all Fibonacci sequences.

LINKS

Table of n, a(n) for n=1..59.

EXAMPLE

6 is a term because (1*1*2*3*5*8) is not divisible by (1+2+3+4+5+6).

5 is not a term because (1*1*2*3*5) is divisible by (1+2+3+4+5).

MATHEMATICA

nn = 800; Function[k, Select[Range@ nn, ! Divisible[k[[#]], # (# + 1)/2] &]]@ FoldList[Times, Array[Fibonacci@ # &, nn]] (* Michael De Vlieger, Mar 19 2016 *)

PROG

(PARI) a(n) = prod(k=1, n, fibonacci(k));

for(n=1, 1e3, if(a(n) % (n*(n+1)/2) != 0, print1(n, ", ")));

CROSSREFS

Cf. A000040, A000057, A003266.

Sequence in context: A073639 A130776 A077292 * A171249 A036413 A069912

Adjacent sequences:  A270472 A270473 A270474 * A270476 A270477 A270478

KEYWORD

nonn

AUTHOR

Altug Alkan, Mar 17 2016

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified September 24 10:18 EDT 2020. Contains 337317 sequences. (Running on oeis4.)