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A162394
Fibonacci numbers (A000045) which are anagrams of Triangular numbers (A000217).
3
0, 1, 3, 21, 55, 2584, 28657, 2178309, 5702887, 14930352, 102334155, 267914296, 701408733, 2971215073, 4807526976, 7778742049, 12586269025, 32951280099, 225851433717, 591286729879, 1548008755920, 10610209857723, 27777890035288, 72723460248141, 308061521170129, 498454011879264, 806515533049393, 1304969544928657, 3416454622906707
OFFSET
1,3
LINKS
Michael S. Branicky, Table of n, a(n) for n = 1..38 (all terms <= 20 digits)
EXAMPLE
2584 is A000045(18) and is an anagram of 2485 = A000217(70).
28567 is A000045(23) and is an anagram of 67528 = A000217(367).
PROG
(Python)
from math import isqrt
from itertools import count, islice
def tris(d): # generator of triangular numbers with d digits
ilb, lb, ub = isqrt(2*10**(d-1))-1, 10**(d-1), 10**d
if d == 1: yield 0
for i in count(ilb):
t = i*(i+1)//2
if t < lb: continue
elif t >= ub: break
yield t
def agen(): # generator of sequence terms
yield 0
f, g, n, adict = 1, 2, 1, dict()
for d in count(1):
T = set("".join(sorted(str(t))) for t in tris(d))
while f < 10**d:
if "".join(sorted(str(f))) in T: yield f
f, g = g, f+g
print(list(islice(agen(), 20))) # Michael S. Branicky, Feb 18 2024
CROSSREFS
Sequence in context: A033567 A181156 A356809 * A129212 A354850 A328042
KEYWORD
nonn,base
AUTHOR
Claudio Meller, Jul 02 2009
EXTENSIONS
Edited and extended by Ray Chandler, Jul 09 2009
a(24)-a(29) from Chai Wah Wu, Dec 25 2016
STATUS
approved