A377457 Numbers k such that k and k+1 are both terms in A377386.

1, 12563307224, 15897851550, 30412355999, 37706988600, 52576459775, 67673545631, 118533901904, 244316235000, 297265003100, 332110595000, 340800265728, 349358409503, 375624917760, 378624889440, 416375389115, 450026519903, 561162864248, 596004199840, 728643460544

Offset

1,2

Links

Amiram Eldar, Table of n, a(n) for n = 1..39

Example

12563307224 is a term since both 12563307224 and 12563307225 are in A377386: 12563307224/A034968(12563307224) = 369509036, 369509036/A034968(369509036) = 9723922 and 9723922/A034968(9723922) = 373997 are integers, and 12563307225/A034968(12563307225) = 358951635, 358951635/A034968(358951635) = 7976703 and 7976703/A034968(7976703) = 257313 are integers.

Prog

(PARI) fdigsum(n) = {my(k = n, m = 2, r, s = 0); while([k, r] = divrem(k, m); k != 0 || r != 0, s += r; m++); s; }
is1(k) = {my(f = fdigsum(k), f2, m); if(k % f, return(0)); m = k/f; f2 = fdigsum(m); !(m % f2) && !((m/f2) % fdigsum(m/f2)); }
lista(kmax) = {my(q1 = is1(1), q2); for(k = 2, kmax, q2 = is1(k); if(q1 && q2, print1(k-1, ", ")); q1 = q2); }

Crossrefs

Cf. A034968.

Subsequence of A118363, A328205, A377385, A377386 and A377455.

Analogous sequences: A376795 (binary), A377272 (Zeckendorf).

Sequence in context: A135496 A287747 A113642 * A329417 A216866 A034657

Adjacent sequences: A377454 A377455 A377456 * A377458 A377459 A377460

Keyword

nonn,base

Author

Amiram Eldar, Oct 29 2024

Status

approved