A350232 - OEIS

A350232

Integers that are divisible by 4 and not by 5, and whose reverse is divisible by 5 and not by 4.

52, 56, 504, 508, 512, 516, 524, 528, 532, 536, 544, 548, 552, 556, 564, 568, 572, 576, 584, 588, 592, 596, 5004, 5008, 5012, 5016, 5024, 5028, 5032, 5036, 5044, 5048, 5052, 5056, 5064, 5068, 5072, 5076, 5084, 5088, 5092, 5096, 5104, 5108, 5112, 5116, 5124, 5128, 5132, 5136, 5144

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,1

COMMENTS

Numbers beginning with 5 and ending with 04, 08, 12, 16, 24, 28, 32, 36, 44, 48, 52, 56, 64, 68, 72, 76, 84, 88, 92, 96. The number of d-digit terms is 2*10^(d-2) for d >= 2. - Jianing Song, Dec 24 2021

LINKS

Table of n, a(n) for n=1..51.

Ana Rechtman, Décembre 2021, 3e défi, Images des Mathématiques, CNRS, 2021.

EXAMPLE

52 is a term since it is divisible by 4 and not by 5, while 25, its reverse, is divisible by 5 and not by 4.

MATHEMATICA

Select[4 * Range[1300], ! Divisible[#, 5] && Divisible[(r = IntegerReverse[#]), 5] && ! Divisible[r, 4] &] (* Amiram Eldar, Dec 21 2021*)

PROG

(PARI) isok(k) = if (!(k%4) && (k%5) , k=fromdigits(Vecrev(digits(k))); !(k%5) && (k%4));

(Python)

from itertools import count, islice

def A350232gen(): return filter(lambda n:(m := int(str(n)[::-1])) % 4 and not m % 5, filter(lambda n: n % 5 and not n % 4, count(1)))

A350232_list = list(islice(A350232gen(), 20)) # Chai Wah Wu, Dec 21 2021

CROSSREFS

Cf. A004086, A350233.

Subsequence of A008586.

Sequence in context: A181461 A346455 A050422 * A226753 A260992 A095537

Adjacent sequences: A350229 A350230 A350231 * A350233 A350234 A350235

KEYWORD

nonn,base

AUTHOR

Michel Marcus, Dec 21 2021

STATUS

approved