A162354 Primes that are anagrams of triangular numbers.

3, 19, 109, 163, 307, 523, 613, 631, 1063, 1117, 1171, 1567, 1657, 1693, 1783, 1801, 1873, 2017, 2251, 2269, 2287, 2521, 2683, 3061, 3079, 3169, 3187, 3457, 3547, 3691, 3709, 3907, 4051, 4357, 4861, 5077, 5167, 5347, 5437, 5563, 5581, 5653, 5743, 5851

Offset

1,1

Comments

19 is an anagram of 91 = T(13) = 13*14/2.

163, 613 and 631 are anagrams of 136 = T(16) = 16*17/2.

Links

Michael S. Branicky, Table of n, a(n) for n = 1..10000

Prog

(Python)
from sympy import primerange
from itertools import count, takewhile
def hash(n): return "".join(sorted(str(n)))
def aupto_digits(d):
    tris   = takewhile(lambda x:x<10**d, (i*(i+1)//2 for i in count(0)))
    primes = primerange(1, 10**d)
    T = set(map(hash, tris))
    return [p for p in primes if hash(p) in T]
print(aupto_digits(4)) # Michael S. Branicky, Feb 18 2024

Crossrefs

Sequence in context: A130425 A334976 A103005 * A132959 A360230 A253811

Adjacent sequences: A162351 A162352 A162353 * A162355 A162356 A162357

Keyword

nonn,base

Author

Claudio Meller, Jul 01 2009

Extensions

Corrected by Claudio Meller, Jul 08 2009

Status

approved