A058994
Numbers m such that 7^m reversed is prime.
Original entry on oeis.org
1, 12, 24, 225, 392, 819, 1201, 1645, 1775, 37578
Offset: 1
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Do[ If[ PrimeQ[ ToExpression[ StringReverse[ ToString[7^n] ] ] ], Print[n] ], {n, 1, 2500} ]
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isok(m) = isprime(fromdigits(Vecrev(digits(7^m)))) \\ Mohammed Yaseen, Jul 20 2022
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from sympy import isprime
k, m, A058994_list = 1, 7, []
while k <= 10**3:
if isprime(int(str(m)[::-1])):
A058994_list.append(k)
k += 1
m *= 7 # Chai Wah Wu, Mar 09 2021
A071586
Powers of 8 written backwards.
Original entry on oeis.org
1, 8, 46, 215, 6904, 86723, 441262, 2517902, 61277761, 827712431, 4281473701, 2954399858, 63767491786, 888318557945, 4011156408934, 23888027348153, 656017679474182, 8425863189971522, 48918490589341081, 278558570881511441
Offset: 0
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for(i=1,50,n=8^i; s=ceil(log(n)/log(10)); print1(sum(i=0,s,10^(s-i-1)*(floor(n/10^i)-10*floor(n/10^(i+1)))),","))
A071588
Powers of 6 written backwards.
Original entry on oeis.org
1, 6, 63, 612, 6921, 6777, 65664, 639972, 6169761, 69677001, 67166406, 650797263, 6332876712, 61049606031, 69046146387, 675489481074, 6547099011282, 63744495662961, 614866659955101, 694010047953906, 6792600448516563
Offset: 0
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FromDigits[Reverse[IntegerDigits[#]]]&/@(6^Range[0,30]) (* Harvey P. Dale, Feb 02 2012 *)
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for(i=1,50,n=5^i; s=ceil(log(n)/log(10)); print1(sum(i=0,s,10^(s-i-1)*(floor(n/10^i)-10*floor(n/10^(i+1)))),","))
Showing 1-3 of 3 results.