A270046 Integers n such that product of first n nonzero Fibonacci numbers (A003266) is the sum of 4 but no fewer nonzero squares.

6, 8, 17, 34, 35, 60, 61, 62, 67, 72, 73, 74, 88, 114, 116, 126, 128, 144, 145, 146, 165, 171, 210, 212, 223, 231, 237, 247, 257, 269, 283, 288, 289, 290, 303, 317, 324, 325, 326, 330, 332, 339, 346, 347, 354, 356, 360, 361, 362, 376, 402, 404, 415, 423, 429, 438, 440

Offset

1,1

Comments

How is the distribution of a(n), a(n+1), a(n+2) in this sequence where a(n+2) = a(n+1) + 1 = a(n) + 2?

Links

Chai Wah Wu, Table of n, a(n) for n = 1..10000

Example

6 is a term because 1*1*2*3*5*8 = 240 and 240 = x^2 + y^2 + z^2 has no solution for integer values of x, y and z.

Prog

(PARI) isA004215(n) = my(fouri, j) ; fouri=1 ; while( n >=7*fouri, if( n % fouri ==0, j= n/fouri-7 ; if( j % 8==0, return(1) ) ; ); fouri *= 4 ; ) ; return(0);
a003266(n) = prod(k=1, n, fibonacci(k));
for(n=1, 1e3, if(isA004215(a003266(n)), print1(n, ", ")));

Crossrefs

Cf. A003266, A004215.

Sequence in context: A345034 A058098 A112158 * A093479 A239396 A340519

Adjacent sequences: A270043 A270044 A270045 * A270047 A270048 A270049

Keyword

nonn

Author

Altug Alkan, Mar 09 2016

Status

approved