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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.)