OFFSET
1,2
COMMENTS
Because A056539(n)/n < 2 for all n, and already for the tenth term of this sequence 1349 we have A235027(1349)/1349 = 2.094... it follows that the only primes present are terms a(2) .. a(7): 11, 19, 67, 71, 263, 271. Conjecture: every term after that is a product of some of those six primes. For example: 781 = 11*71, 1273 = 19*67, 1349 = 19*71, 2981 = 11*271, 4757 = 67*71, 5041 = 71*71.
PROG
(PARI)
revbits(n) = fromdigits(Vecrev(binary(n)), 2);
A235027(n) = {my(f = factor(n)); for (k=1, #f~, if (f[k, 1] != 2, f[k, 1] = revbits(f[k, 1]); ); ); factorback(f); } \\ This function from Michel Marcus, Aug 05 2017
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Antti Karttunen, Aug 07 2017
STATUS
approved