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A120804 Primes with consecutive digits descending. 5
2, 3, 5, 7, 43, 109, 10987, 76543, 10987654321098765432109876543210987, 4321098765432109876543210987654321098765432109876543210987654321 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Digits can be in descending order. After 0 comes 9.

a(15) has 1053 digits. - Michael S. Branicky, Aug 05 2022

LINKS

Paul Tek, Table of n, a(n) for n = 1..14

MATHEMATICA

f[n_] := Block[{d = Reverse@ Range@n, t = Table[1, {n}]}, Select[ Drop[ Union@ Flatten@ Table[ FromDigits[ Mod[d + i*t, 10]], {i, 10}], 2], PrimeQ@# &]]; Array[f, 1000] // Flatten

PROG

(Python)

from sympy import isprime

from itertools import count, islice

def bgen(): yield from (int("".join(str((s0-i)%10) for i in range(d))) for d in count(1) for s0 in range(1, 10))

def agen(): yield from filter(isprime, bgen())

print(list(islice(agen(), 10))) # Michael S. Branicky, Aug 05 2022

CROSSREFS

Cf. A006055, A120805.

Sequence in context: A083820 A244556 A279954 * A092066 A224904 A028981

Adjacent sequences: A120801 A120802 A120803 * A120805 A120806 A120807

KEYWORD

nonn,base

AUTHOR

Robert G. Wilson v, Jul 05 2006

EXTENSIONS

Corrected by Paul Tek, May 08 2013

STATUS

approved

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Last modified December 7 01:51 EST 2022. Contains 358649 sequences. (Running on oeis4.)