This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A291321 #24 May 06 2025 11:00:13 %S A291321 1012658227848,1139240506329,10126582278481012658227848, %T A291321 11392405063291139240506329,101265822784810126582278481012658227848, %U A291321 113924050632911392405063291139240506329,1012658227848101265822784810126582278481012658227848 %N A291321 Numbers m with the property that shifting the rightmost digit of m to the left end multiplies the number by 8. %C A291321 Let x = (10^12 - 8)/79 = 12658227848. Then a(1) = 8*x*10 + 8, a(2) = 9*x*10 + 9. %C A291321 For consistency with A146088 (similar for ratio k=2) and others, where an initial a(0) = 0 has been added, the same could be considered here. It would be compatible with the formula given for a(2k). - _M. F. Hasler_, May 03 2025 %H A291321 Seiichi Manyama, <a href="/A291321/b291321.txt">Table of n, a(n) for n = 1..152</a> %H A291321 Wikipedia, <a href="https://en.wikipedia.org/wiki/Parasitic_number">Parasitic number</a>. %F A291321 a(2*k - 1) = 8*(10^(13*k) - 1)/79. %F A291321 a(2*k) = 9*(10^(13*k) - 1)/79. %e A291321 a(1) = b*10 + 8 with b = 101265822784, and 8*a(1) = 8101265822784 = 8*10^12 + b. %o A291321 (PARI) a(n)=10^((n+1)\2*13)\79*(9-n%2) \\ _Charles R Greathouse IV_, Aug 23 2017 %Y A291321 Cf. A146088 (k=2), A146561 (k=3), A146569 (k=4), A146754 (k=5), A291354 (k=6), A291215 (k=7), this sequence (k=8), A291353 (k=9). %Y A291321 All these are subsequences of A034089 (except for an initial 0 in some of them). %Y A291321 Cf. A092697, A097717. %K A291321 nonn,base,easy %O A291321 1,1 %A A291321 _Seiichi Manyama_, Aug 22 2017 %E A291321 Edited by _M. F. Hasler_, May 03 2025