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 A346756 Lesser emirps (A109308) subtracted from their reversals. 1
 18, 54, 36, 18, 594, 198, 792, 594, 594, 792, 792, 396, 396, 594, 594, 198, 198, 198, 7992, 180, 270, 2268, 540, 8532, 810, 6804, 1908, 7902, 360, 2358, 630, 2718, 1908, 5904, 1998, 7992, 90, 6084, 8172, 8262, 8442, 2538, 450, 8532, 7632, 7812, 7902, 2088, 270 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Robert Israel, Table of n, a(n) for n = 1..10000 Carlos Rivera, Puzzle 20. Reversible Primes, The Prime Puzzles and Problems Connection. FORMULA a(n) = reverse(A109308(n)) - A109308(n). EXAMPLE 31 - 13 = 18, 71 - 17 = 54, 73 - 37 = 36 (distance between lesser emirps and their reversals). MAPLE rev:= proc(n) local L, i; L:= convert(n, base, 10); add(L[-i]*10^(i-1), i=1..nops(L)); end proc: f:= proc(p) local r; if not isprime(p) then return NULL fi; r:= rev(p); if r > p and isprime(r) then r-p else NULL fi end proc: map(f, [seq(i, i=11 .. 10^4, 2)]); # Robert Israel, Dec 28 2023 MATHEMATICA f[n_] := IntegerReverse[n] - n; Map[f, Select[Range[1500], f[#] > 0 && PrimeQ[#] && PrimeQ @ IntegerReverse[#] &]] (* Amiram Eldar, Sep 08 2021 *) PROG (PARI) rev(p) = fromdigits(Vecrev(digits(p))); \\ A004086 lista(nn) = {my(list = List()); forprime (p=1, nn, my(q=rev(p)); if ((q>p) && isprime(q), listput(list, q-p)); ); Vec(list); } \\ Michel Marcus, Sep 07 2021 (Python) from sympy import isprime, nextprime def aupton(terms): alst, p = [], 2 while len(alst) < terms: revp = int(str(p)[::-1]) if p < revp and isprime(revp): alst.append(revp - p) p = nextprime(p) return alst print(aupton(49)) # Michael S. Branicky, Sep 08 2021 CROSSREFS Cf. A004086, A006567, A109308. Sequence in context: A052902 A217591 A059137 * A096011 A176026 A068396 Adjacent sequences: A346753 A346754 A346755 * A346757 A346758 A346759 KEYWORD nonn,base,look AUTHOR George Bull, Aug 20 2021 EXTENSIONS Better name and more terms from Jon E. Schoenfield, Aug 20 2021 STATUS approved

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Last modified February 29 04:20 EST 2024. Contains 370401 sequences. (Running on oeis4.)