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A124095
Happy numbers without zeros and with digits in nondecreasing order.
4
1, 7, 13, 19, 23, 28, 44, 49, 68, 79, 129, 133, 139, 167, 188, 226, 236, 239, 338, 356, 367, 368, 379, 446, 469, 478, 556, 566, 888, 899, 1112, 1114, 1115, 1122, 1125, 1128, 1148, 1158, 1177, 1188, 1222, 1233, 1247, 1257, 1258, 1277, 1288, 1299, 1333, 1335
OFFSET
0,2
PROG
(Python)
from itertools import count, islice, combinations_with_replacement
def A124095_gen(): # generator of terms
for l in count(1):
for m in combinations_with_replacement('123456789', l):
k = t = int(''.join(m))
while k not in {1, 37, 58, 89, 145, 42, 20, 4, 16}:
k = sum((0, 1, 4, 9, 16, 25, 36, 49, 64, 81)[ord(d)-48] for d in str(k))
if k == 1:
yield t
A124095_list = list(islice(A124095_gen(), 20)) # Chai Wah Wu, Aug 02 2023
CROSSREFS
Cf. A007770 (Happy numbers), A068571, A219667.
Sequence in context: A121058 A007921 A092409 * A109369 A336373 A320629
KEYWORD
base,nonn
AUTHOR
Tanya Khovanova, Nov 25 2006
STATUS
approved