40r71s6j25Q+ȷỌżŒl$
A full program. Pretty similar in nature to an existing answer by Erik the Outgolfer, but I think it's different enough.
Try it online!
How?
40r71s6j25Q+ȷỌżŒl$ Main link: no arguments
40r71 inclusive range from 40 to 71: [40,41,42,43,44,45,46,47,48,49,50,51,52,53,54,55,56,57,58,59,60,61,62,63,64,65,66,67,68,69,70,71]
s6 split into sixes: [[40,41,42,43,44,45],[46,47,48,49,50,51],[52,53,54,55,56,57],[58,59,60,61,62,63],[64,65,66,67,68,69],[70,71]]
j25 join with 25s: [40,41,42,43,44,45,25,46,47,48,49,50,51,25,52,53,54,55,56,57,25,58,59,60,61,62,63,25,64,65,66,67,68,69,25,70,71]
Q de-duplicate: [40,41,42,43,44,45,25,46,47,48,49,50,51,52,53,54,55,56,57,58,59,60,61,62,63,64,65,66,67,68,69,70,71]
ȷ literal 1000
+ addition: [1040,1041,1042,1043,1044,1045,1025,1046,1047,1048,1049,1050,1051,1052,1053,1054,1055,1056,1057,1058,1059,1060,1061,1062,1063,1064,1065,1066,1067,1068,1069,1070,1071]
Ọ cast to characters: "АБВГДЕЁЖЗИЙКЛМНОПРСТУФХЦЧШЩЪЫЬЭЮЯ"
$ last two links as a monad:
Œl lowercase: "абвгдеёжзийклмнопрстуфхцчшщъыьэюя"
ż zip: ["Аа","Бб","Вв","Гг","Дд","Ее","Ёё","Жж","Зз","Ии","Йй","Кк","Лл","Мм","Нн","Оо","Пп","Рр","Сс","Тт","Уу","Фф","Хх","Цц","Чч","Шш","Щщ","Ъъ","Ыы","Ьь","Ээ","Юю","Яя"]
implicit print: АаБбВвГгДдЕеЁёЖжЗзИиЙйКкЛлМмНнОоПпРрСсТтУуФфХхЦцЧчШшЩщЪъЫыЬьЭэЮюЯя
Ёё
, may we output codepoints U+00CB and U+00EB instead of U+0401 and U+0451? \$\endgroup\$