A391858 Numbers k such that 25*k = A048720(m, k) for some m, where A048720 is carryless base-2 multiplication.

0, 1, 2, 3, 4, 5, 6, 7, 8, 10, 12, 14, 16, 20, 24, 28, 31, 32, 33, 40, 48, 51, 56, 62, 63, 64, 65, 66, 80, 93, 95, 96, 102, 112, 124, 125, 126, 127, 128, 129, 130, 132, 133, 160, 161, 186, 190, 191, 192, 204, 224, 248, 250, 252, 253, 254, 255, 256, 257, 258, 260, 261, 264, 266, 320, 321, 322, 372, 380, 381, 382, 383

Offset

1,3

Comments

If n is a term, then 2*n is also a term, and vice versa. See A391859 for the odd terms.

Links

Antti Karttunen, Table of n, a(n) for n = 1..10000

Index entries for sequences defined by congruent products between domains N and GF(2)[X].

Index entries for sequences related to binary expansion of n.

Index entries for sequences related to carryless arithmetic.

Formula

{0 followed by k such that A280500(25*k, k) = m for some m > 0}.

Example

3 is a term as 25*3 = A048720(57,3) = 75.
5 is a term as 25*5 = A048720(25,5) = 125.
31 is a term as 25*31 = A048720(41,31) = 775.

Prog

(PARI) is_A391858(k) = (!k || (0==lift(Pol(binary(25*k)*Mod(1, 2)) % Pol(binary(k))*Mod(1, 2))));

Crossrefs

Cf. A048720, A280500.

Row 25 of A391925.

Subsequences: A391737 (m=25), A391738 (m=41), A391739 (m=57), A391859 (odd terms).

Cf. also A391744, A391860.

Sequence in context: A060471 A003045 A279079 * A391854 A029750 A266480

Adjacent sequences: A391855 A391856 A391857 * A391859 A391860 A391861

Keyword

nonn,base

Author

Antti Karttunen, Dec 21 2025

Status

approved