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 A088116 Let n = abc..., where a, b, c, are digits of n. a(n) = a*bc...+b*ac...+c*ab...+..., i.e., a(n) = sum, over all the digits, of the product (number obtained by deleting a digit multiplied by the deleted digit). 3
 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, 4, 6, 8, 10, 12, 14, 16, 18, 0, 4, 8, 12, 16, 20, 24, 28, 32, 36, 0, 6, 12, 18, 24, 30, 36, 42, 48, 54, 0, 8, 16, 24, 32, 40, 48, 56, 64, 72, 0, 10, 20, 30, 40, 50, 60, 70, 80, 90, 0, 12, 24, 36, 48, 60, 72, 84, 96, 108, 0, 14, 28, 42, 56, 70, 84, 98 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,12 COMMENTS First 100 terms (for all two digit numbers) match with that of A069816. A088116(10a + b) = 2ab = (a+b)^2 - (a^2 + b^2) = A069816(10a + b). The first known fixed points, after zero, are numbers of the forms 36*10^k and 1314*10^k for k >= 0. All have 9 as the sum of their digits. Calculated up to n = 10^10. - Stéphane Rézel, Jul 31 2019 LINKS Jinyuan Wang, Table of n, a(n) for n = 0..10000 EXAMPLE a(1234) = 234 + 2*134 + 3*124 + 4*123 = 1366. PROG (PARI) a(n) = {v=digits(n); sum(k=1, #v, v[k]*(n\10^(#v-k+1)*10^(#v-k)+n%10^(#v-k))); } \\ Jinyuan Wang, Aug 01 2019 CROSSREFS Cf. A069816, A087346, A088117. Sequence in context: A241142 A271907 A069816 * A100817 A074157 A076309 Adjacent sequences:  A088113 A088114 A088115 * A088117 A088118 A088119 KEYWORD base,easy,nonn AUTHOR Amarnath Murthy, Sep 25 2003 EXTENSIONS More terms from David Wasserman, May 10 2005 Offset 0 from Stéphane Rézel, Jul 31 2019 STATUS approved

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Last modified September 18 19:30 EDT 2021. Contains 347534 sequences. (Running on oeis4.)