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A355430
Primes starting with an even decimal digit.
5
2, 23, 29, 41, 43, 47, 61, 67, 83, 89, 211, 223, 227, 229, 233, 239, 241, 251, 257, 263, 269, 271, 277, 281, 283, 293, 401, 409, 419, 421, 431, 433, 439, 443, 449, 457, 461, 463, 467, 479, 487, 491, 499, 601, 607, 613, 617, 619, 631, 641, 643, 647, 653, 659, 661, 673, 677, 683, 691, 809, 811, 821
OFFSET
1,1
COMMENTS
Primes whose reversal is an even integer.
LINKS
EXAMPLE
43 is a term because 43 is prime and 34 is an even number.
MATHEMATICA
imax=142; a={}; For[i=1, i<=imax, i++, If[EvenQ[FromDigits[Reverse[IntegerDigits[Prime[i]]]]], AppendTo[a, Prime[i]]]]; a (* Stefano Spezia, Jul 20 2022 *)
PROG
(PARI) isok(k) = isprime(k) && !(fromdigits(Vecrev(digits(k))) % 2); \\ Michel Marcus, Jul 20 2022
(Python)
from sympy import isprime
def ok(n): return str(n)[0] in "2468" and isprime(n)
print([k for k in range(822) if ok(k)]) # Michael S. Branicky, Jul 25 2022
(Python)
from sympy import isprime
from itertools import chain, count, islice, product
def agen(): yield from chain((2, ), (t for t in (b+i for d in count(1) for b in range(2*10**d, 10*10**d, 2*10**d) for i in range(1, 10**d, 2)) if isprime(t)))
print(list(islice(agen(), 62))) # Michael S. Branicky, Jul 25 2022
CROSSREFS
Intersection of A000040 and A273892.
Equals disjoint union of A045708, A045710, A045712 and A045714.
Primes whose reversal is a multiple of k: this sequence (k=2), {3} (k=3), A045711 (k=5), A087762 (k=7), {11} (k=11), A087764 (k=13), A087765 (k=17), A087766 (k=19), A087767 (k=23).
Sequence in context: A045391 A154758 A156614 * A226016 A235150 A114549
KEYWORD
nonn,base
AUTHOR
Bernard Schott, Jul 20 2022
STATUS
approved