A124095 Happy numbers without zeros and with digits in nondecreasing order.

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

Links

Bryan Wolf, Table of n, a(n) for n = 0..13376 (terms < 10^10))

Bryan Wolf, C++ program for generating happy numbers without zeros and with digits in non-decreasing order

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

Adjacent sequences: A124092 A124093 A124094 * A124096 A124097 A124098

Keyword

base,nonn

Author

Tanya Khovanova, Nov 25 2006

Status

approved